Merge pull request #206 from Minestom/item-api

New Item API

src/lwjgl/java/net/minestom/demo/largeframebuffers/Demo.java

@@ -68,8 +68,9 @@ public class Demo {
     private static void createFrame(Instance instance, int id, int x, int y, int z) {
         EntityItemFrame itemFrame = new EntityItemFrame(new Position(x, y, z), EntityItemFrame.ItemFrameOrientation.NORTH);
         itemFrame.getPosition().setYaw(180f);
-        ItemStack map = new ItemStack(Material.FILLED_MAP, (byte) 1);
+        ItemStack map = ItemStack.builder(Material.FILLED_MAP)
-        map.setItemMeta(new MapMeta(id));
+                .meta(new MapMeta.Builder().mapId(id).build())
+                .build();
         itemFrame.setItemStack(map);
         itemFrame.setInstance(instance);
         itemFrame.setCustomNameVisible(true);

src/main/java/net/minestom/server/advancements/Advancement.java

@@ -60,7 +60,7 @@ public class Advancement {
     public Advancement(@NotNull JsonMessage title, @NotNull JsonMessage description,
                        @NotNull Material icon, @NotNull FrameType frameType,
                        float x, float y) {
-        this(title, description, new ItemStack(icon, (byte) 1), frameType, x, y);
+        this(title, description, ItemStack.of(icon), frameType, x, y);
     }
 
     public Advancement(@NotNull Component title, Component description,
@@ -77,7 +77,7 @@ public class Advancement {
     public Advancement(@NotNull Component title, @NotNull Component description,
                        @NotNull Material icon, @NotNull FrameType frameType,
                        float x, float y) {
-        this(title, description, new ItemStack(icon, (byte) 1), frameType, x, y);
+        this(title, description, ItemStack.of(icon), frameType, x, y);
     }
 
     /**

src/main/java/net/minestom/server/advancements/notifications/Notification.java

@@ -33,7 +33,7 @@ public class Notification {
     }
 
     public Notification(@NotNull Component title, @NotNull FrameType frameType, @NotNull Material icon) {
-        this(title, frameType, new ItemStack(icon, (byte) 1));
+        this(title, frameType, ItemStack.of(icon));
     }
 
     public Notification(@NotNull Component title, @NotNull FrameType frameType, @NotNull ItemStack icon) {
@@ -46,7 +46,6 @@ public class Notification {
      * Gets the title of the notification.
      *
      * @return the notification title
-     *
      * @deprecated Use {@link #getTitle()}
      */
     @NotNull

src/main/java/net/minestom/server/chat/ChatHoverEvent.java

@@ -10,12 +10,12 @@ import net.minestom.server.entity.EntityType;
 import net.minestom.server.item.ItemStack;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
 import java.util.UUID;
 
 /**
  * Represents a hover event for a specific portion of the message.
+ *
  * @deprecated Use {@link HoverEvent}
  */
 @Deprecated
@@ -93,11 +93,8 @@ public class ChatHoverEvent {
         JsonObject obj = GsonComponentSerializer.gson().serializer().toJsonTree(Component.empty().hoverEvent(event)).getAsJsonObject();
         obj = obj.get("hoverEvent").getAsJsonObject().get("contents").getAsJsonObject();
 
-        if (itemStack.getItemMeta() != null) {
+        final String snbt = itemStack.getMeta().toSNBT();
-            NBTCompound compound = new NBTCompound();
+        obj.add("tag", new JsonPrimitive(snbt));
-            itemStack.getItemMeta().write(compound);
-            obj.add("tag", new JsonPrimitive(compound.toSNBT()));
-        }
 
         return new ChatHoverEvent("show_item", obj);
     }

src/main/java/net/minestom/server/command/builder/arguments/minecraft/ArgumentItemStack.java

@@ -42,13 +42,11 @@ public class ArgumentItemStack extends Argument<ItemStack> {
         if (nbtIndex == -1) {
             // Only item name
             final Material material = Registries.getMaterial(input);
-            return new ItemStack(material, (byte) 1);
+            return ItemStack.of(material);
         } else {
             final String materialName = input.substring(0, nbtIndex);
             final Material material = Registries.getMaterial(materialName);
 
-            ItemStack itemStack = new ItemStack(material, (byte) 1);
-
             final String sNBT = input.substring(nbtIndex).replace("\\\"", "\"");
 
             NBTCompound compound;
@@ -58,9 +56,7 @@ public class ArgumentItemStack extends Argument<ItemStack> {
                 throw new ArgumentSyntaxException("Item NBT is invalid", input, INVALID_NBT);
             }
 
-            NBTUtils.loadDataIntoItem(itemStack, compound);
+            return NBTUtils.loadItem(material, 1, compound);
-
-            return itemStack;
         }
     }
 

src/main/java/net/minestom/server/data/type/InventoryData.java

@@ -1,5 +1,6 @@
 package net.minestom.server.data.type;
 
+import net.kyori.adventure.text.Component;
 import net.minestom.server.data.DataType;
 import net.minestom.server.inventory.Inventory;
 import net.minestom.server.inventory.InventoryType;
@@ -15,7 +16,7 @@ public class InventoryData extends DataType<Inventory> {
         final int size = inventoryType.getSize();
 
         // Inventory title & type
-        writer.writeSizedString(value.getTitle());
+        writer.writeComponent(value.getTitle());
         writer.writeSizedString(inventoryType.name());
 
         // Write all item stacks
@@ -27,7 +28,7 @@ public class InventoryData extends DataType<Inventory> {
     @NotNull
     @Override
     public Inventory decode(@NotNull BinaryReader reader) {
-        final String title = reader.readSizedString(Integer.MAX_VALUE);
+        final Component title = reader.readComponent(Integer.MAX_VALUE);
         final InventoryType inventoryType = InventoryType.valueOf(reader.readSizedString(Integer.MAX_VALUE));
         final int size = inventoryType.getSize();
 

src/main/java/net/minestom/server/entity/ItemEntity.java

@@ -109,7 +109,7 @@ public class ItemEntity extends ObjectEntity {
                     if (!canApply)
                         continue;
 
-                    final ItemStack result = stackingRule.apply(itemStack.clone(), totalAmount);
+                    final ItemStack result = stackingRule.apply(itemStack, totalAmount);
 
                     EntityItemMergeEvent entityItemMergeEvent = new EntityItemMergeEvent(this, itemEntity, result);
                     callCancellableEvent(EntityItemMergeEvent.class, entityItemMergeEvent, () -> {

src/main/java/net/minestom/server/entity/LivingEntity.java

@@ -37,7 +37,7 @@ import java.util.concurrent.ConcurrentHashMap;
 //TODO: Default attributes registration (and limitation ?)
 public class LivingEntity extends Entity implements EquipmentHandler {
 
-    // Item pickup
+    // ItemStack pickup
     protected boolean canPickupItem;
     protected Cooldown itemPickupCooldown = new Cooldown(new UpdateOption(5, TimeUnit.TICK));
 
@@ -111,13 +111,13 @@ public class LivingEntity extends Entity implements EquipmentHandler {
     }
 
     private void initEquipments() {
-        this.mainHandItem = ItemStack.getAirItem();
+        this.mainHandItem = ItemStack.AIR;
-        this.offHandItem = ItemStack.getAirItem();
+        this.offHandItem = ItemStack.AIR;
 
-        this.helmet = ItemStack.getAirItem();
+        this.helmet = ItemStack.AIR;
-        this.chestplate = ItemStack.getAirItem();
+        this.chestplate = ItemStack.AIR;
-        this.leggings = ItemStack.getAirItem();
+        this.leggings = ItemStack.AIR;
-        this.boots = ItemStack.getAirItem();
+        this.boots = ItemStack.AIR;
     }
 
     @NotNull

src/main/java/net/minestom/server/entity/Metadata.java

@@ -343,7 +343,7 @@ public class Metadata {
             case TYPE_OPTCHAT:
                 return (Value<T>) OptChat((Component) null);
             case TYPE_SLOT:
-                return (Value<T>) Slot(ItemStack.getAirItem());
+                return (Value<T>) Slot(ItemStack.AIR);
             case TYPE_BOOLEAN:
                 return (Value<T>) Boolean(false);
             case TYPE_ROTATION:

src/main/java/net/minestom/server/entity/Player.java

@@ -68,6 +68,7 @@ import net.minestom.server.utils.chunk.ChunkCallback;
 import net.minestom.server.utils.chunk.ChunkUtils;
 import net.minestom.server.utils.entity.EntityUtils;
 import net.minestom.server.utils.instance.InstanceUtils;
+import net.minestom.server.utils.inventory.PlayerInventoryUtils;
 import net.minestom.server.utils.time.Cooldown;
 import net.minestom.server.utils.time.TimeUnit;
 import net.minestom.server.utils.time.UpdateOption;
@@ -589,14 +590,6 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
             }
         }
 
-        // Item ownership cache
-        {
-            ItemStack[] itemStacks = inventory.getItemStacks();
-            for (ItemStack itemStack : itemStacks) {
-                ItemStack.DATA_OWNERSHIP.clearCache(itemStack.getIdentifier());
-            }
-        }
-
         // Clear all viewable entities
         this.viewableEntities.forEach(entity -> entity.removeViewer(this));
         // Clear all viewable chunks
@@ -1096,42 +1089,16 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
         MinecraftServer.getBossBarManager().removeBossBar(this, bar);
     }
 
-    /**
-     * Opens a book ui for the player with the given book metadata.
-     *
-     * @param bookMeta The metadata of the book to open
-     * @deprecated Use {@link #openBook(Book)}
-     */
-    @Deprecated
-    public void openBook(@NotNull WrittenBookMeta bookMeta) {
-        // Set book in offhand
-        final ItemStack writtenBook = new ItemStack(Material.WRITTEN_BOOK, (byte) 1);
-        writtenBook.setItemMeta(bookMeta);
-        final SetSlotPacket setSlotPacket = new SetSlotPacket();
-        setSlotPacket.windowId = 0;
-        setSlotPacket.slot = 45;
-        setSlotPacket.itemStack = writtenBook;
-        this.playerConnection.sendPacket(setSlotPacket);
-
-        // Open the book
-        final OpenBookPacket openBookPacket = new OpenBookPacket();
-        openBookPacket.hand = Hand.OFF;
-        this.playerConnection.sendPacket(openBookPacket);
-
-        // Update inventory to remove book (which the actual inventory does not have)
-        this.inventory.update();
-    }
-
     @Override
     public void openBook(@NotNull Book book) {
-        // make the book
+        ItemStack writtenBook = ItemStack.builder(Material.WRITTEN_BOOK)
-        ItemStack writtenBook = new ItemStack(Material.WRITTEN_BOOK, (byte) 1);
+                .meta(WrittenBookMeta.fromAdventure(book, this))
-        writtenBook.setItemMeta(WrittenBookMeta.fromAdventure(book, this));
+                .build();
 
         // Set book in offhand
         SetSlotPacket setBookPacket = new SetSlotPacket();
         setBookPacket.windowId = 0;
-        setBookPacket.slot = 45;
+        setBookPacket.slot = PlayerInventoryUtils.OFFHAND_SLOT;
         setBookPacket.itemStack = writtenBook;
         playerConnection.sendPacket(setBookPacket);
 
@@ -1143,7 +1110,7 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
         // Restore the item in offhand
         SetSlotPacket restoreItemPacket = new SetSlotPacket();
         restoreItemPacket.windowId = 0;
-        restoreItemPacket.slot = 45;
+        restoreItemPacket.slot = PlayerInventoryUtils.OFFHAND_SLOT;
         restoreItemPacket.itemStack = getItemInOffHand();
         playerConnection.sendPacket(restoreItemPacket);
     }
@@ -1996,10 +1963,10 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
         ItemStack cursorItem;
         if (openInventory == null) {
             cursorItem = getInventory().getCursorItem();
-            getInventory().setCursorItem(ItemStack.getAirItem());
+            getInventory().setCursorItem(ItemStack.AIR);
         } else {
             cursorItem = openInventory.getCursorItem(this);
-            openInventory.setCursorItem(this, ItemStack.getAirItem());
+            openInventory.setCursorItem(this, ItemStack.AIR);
         }
         if (!cursorItem.isAir()) {
             // Add item to inventory if he hasn't been able to drop it

src/main/java/net/minestom/server/entity/fakeplayer/FakePlayerController.java

@@ -4,7 +4,7 @@ import net.minestom.server.entity.Entity;
 import net.minestom.server.entity.Player;
 import net.minestom.server.instance.block.BlockFace;
 import net.minestom.server.inventory.Inventory;
-import net.minestom.server.inventory.InventoryModifier;
+import net.minestom.server.inventory.AbstractInventory;
 import net.minestom.server.inventory.PlayerInventory;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.network.packet.client.ClientPlayPacket;
@@ -48,12 +48,12 @@ public class FakePlayerController {
      */
     public void clickWindow(boolean playerInventory, short slot, byte button, short action, int mode) {
         Inventory inventory = playerInventory ? null : fakePlayer.getOpenInventory();
-        InventoryModifier inventoryModifier = inventory == null ? fakePlayer.getInventory() : inventory;
+        AbstractInventory abstractInventory = inventory == null ? fakePlayer.getInventory() : inventory;
-        playerInventory = inventoryModifier instanceof PlayerInventory;
+        playerInventory = abstractInventory instanceof PlayerInventory;
 
         slot = playerInventory ? (short) PlayerInventoryUtils.convertToPacketSlot(slot) : slot;
 
-        ItemStack itemStack = inventoryModifier.getItemStack(slot);
+        ItemStack itemStack = abstractInventory.getItemStack(slot);
 
         ClientClickWindowPacket clickWindowPacket = new ClientClickWindowPacket();
         clickWindowPacket.windowId = playerInventory ? 0 : inventory.getWindowId();

src/main/java/net/minestom/server/entity/metadata/item/ItemContainingMeta.java

@@ -13,7 +13,7 @@ class ItemContainingMeta extends EntityMeta {
 
     protected ItemContainingMeta(@NotNull Entity entity, @NotNull Metadata metadata, @NotNull Material defaultItemMaterial) {
         super(entity, metadata);
-        this.defaultItem = new ItemStack(defaultItemMaterial, (byte) 1);
+        this.defaultItem = ItemStack.of(defaultItemMaterial);
     }
 
     @NotNull

src/main/java/net/minestom/server/entity/metadata/other/FireworkRocketMeta.java

@@ -18,7 +18,7 @@ public class FireworkRocketMeta extends EntityMeta implements ProjectileMeta {
 
     @NotNull
     public ItemStack getFireworkInfo() {
-        return super.metadata.getIndex((byte) 7, ItemStack.getAirItem());
+        return super.metadata.getIndex((byte) 7, ItemStack.AIR);
     }
 
     public void setFireworkInfo(@NotNull ItemStack value) {

src/main/java/net/minestom/server/entity/metadata/other/ItemFrameMeta.java

@@ -19,7 +19,7 @@ public class ItemFrameMeta extends EntityMeta implements ObjectDataProvider {
 
     @NotNull
     public ItemStack getItem() {
-        return super.metadata.getIndex((byte) 7, ItemStack.getAirItem());
+        return super.metadata.getIndex((byte) 7, ItemStack.AIR);
     }
 
     public void setItem(@NotNull ItemStack value) {

src/main/java/net/minestom/server/entity/type/decoration/EntityArmorStand.java

@@ -41,13 +41,13 @@ public class EntityArmorStand extends ObjectEntity implements EquipmentHandler {
         setLeftLegRotation(new Vector(-1f, 0, -1f));
         setRightLegRotation(new Vector(1, 0, 1));
 
-        this.mainHandItem = ItemStack.getAirItem();
+        this.mainHandItem = ItemStack.AIR;
-        this.offHandItem = ItemStack.getAirItem();
+        this.offHandItem = ItemStack.AIR;
 
-        this.helmet = ItemStack.getAirItem();
+        this.helmet = ItemStack.AIR;
-        this.chestplate = ItemStack.getAirItem();
+        this.chestplate = ItemStack.AIR;
-        this.leggings = ItemStack.getAirItem();
+        this.leggings = ItemStack.AIR;
-        this.boots = ItemStack.getAirItem();
+        this.boots = ItemStack.AIR;
 
     }
 

src/main/java/net/minestom/server/entity/type/decoration/EntityItemFrame.java

@@ -10,6 +10,7 @@ import org.jetbrains.annotations.NotNull;
 
 // FIXME: https://wiki.vg/Object_Data#Item_Frame_.28id_71.29
 // "You have to set both Orientation and Yaw/Pitch accordingly, otherwise it will not work."
+
 /**
  * @deprecated Use {@link net.minestom.server.entity.metadata.other.ItemFrameMeta} instead.
  */
@@ -37,7 +38,7 @@ public class EntityItemFrame extends ObjectEntity {
      */
     @NotNull
     public ItemStack getItemStack() {
-        return metadata.getIndex((byte) 7, ItemStack.getAirItem());
+        return metadata.getIndex((byte) 7, ItemStack.AIR);
     }
 
     /**

src/main/java/net/minestom/server/entity/type/projectile/EntityEyeOfEnder.java

@@ -26,7 +26,7 @@ public class EntityEyeOfEnder extends Entity {
      * @return the item
      */
     public ItemStack getItemStack() {
-        return metadata.getIndex((byte) 7, ItemStack.getAirItem());
+        return metadata.getIndex((byte) 7, ItemStack.AIR);
     }
 
     /**

src/main/java/net/minestom/server/entity/type/projectile/EntityPotion.java

@@ -22,7 +22,7 @@ public class EntityPotion extends Entity {
 
     @NotNull
     public ItemStack getPotion() {
-        return metadata.getIndex((byte) 7, ItemStack.getAirItem());
+        return metadata.getIndex((byte) 7, ItemStack.AIR);
     }
 
     public void setPotion(@NotNull ItemStack potion) {

src/main/java/net/minestom/server/event/player/PlayerAddItemStackEvent.java

@@ -1,51 +0,0 @@
-package net.minestom.server.event.player;
-
-import net.minestom.server.entity.Player;
-import net.minestom.server.event.CancellableEvent;
-import net.minestom.server.event.PlayerEvent;
-import net.minestom.server.item.ItemStack;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Called as a result of {@link net.minestom.server.inventory.PlayerInventory#addItemStack(ItemStack)}.
- */
-public class PlayerAddItemStackEvent extends PlayerEvent implements CancellableEvent {
-
-    private ItemStack itemStack;
-
-    private boolean cancelled;
-
-    public PlayerAddItemStackEvent(@NotNull Player player, @NotNull ItemStack itemStack) {
-        super(player);
-        this.itemStack = itemStack;
-    }
-
-    /**
-     * Gets the item stack which will be added.
-     *
-     * @return the item stack
-     */
-    @NotNull
-    public ItemStack getItemStack() {
-        return itemStack;
-    }
-
-    /**
-     * Changes the item stack which will be added.
-     *
-     * @param itemStack the new item stack
-     */
-    public void setItemStack(@NotNull ItemStack itemStack) {
-        this.itemStack = itemStack;
-    }
-
-    @Override
-    public boolean isCancelled() {
-        return cancelled;
-    }
-
-    @Override
-    public void setCancelled(boolean cancel) {
-        this.cancelled = cancel;
-    }
-}

src/main/java/net/minestom/server/event/player/PlayerSetItemStackEvent.java

@@ -1,72 +0,0 @@
-package net.minestom.server.event.player;
-
-import net.minestom.server.entity.Player;
-import net.minestom.server.event.CancellableEvent;
-import net.minestom.server.event.PlayerEvent;
-import net.minestom.server.item.ItemStack;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Called as a result of {@link net.minestom.server.inventory.PlayerInventory#setItemStack(int, ItemStack)}
- * and player click in his inventory.
- */
-public class PlayerSetItemStackEvent extends PlayerEvent implements CancellableEvent {
-
-    private int slot;
-    private ItemStack itemStack;
-
-    private boolean cancelled;
-
-    public PlayerSetItemStackEvent(@NotNull Player player, int slot, @NotNull ItemStack itemStack) {
-        super(player);
-        this.slot = slot;
-        this.itemStack = itemStack;
-    }
-
-    /**
-     * Gets the slot where the item will be set.
-     *
-     * @return the slot
-     */
-    public int getSlot() {
-        return slot;
-    }
-
-    /**
-     * Changes the slot where the item will be set.
-     *
-     * @param slot the new slot
-     */
-    public void setSlot(int slot) {
-        this.slot = slot;
-    }
-
-    /**
-     * Gets the item stack which will be set.
-     *
-     * @return the item stack
-     */
-    @NotNull
-    public ItemStack getItemStack() {
-        return itemStack;
-    }
-
-    /**
-     * Changes the item stack which will be set.
-     *
-     * @param itemStack the new item stack
-     */
-    public void setItemStack(@NotNull ItemStack itemStack) {
-        this.itemStack = itemStack;
-    }
-
-    @Override
-    public boolean isCancelled() {
-        return cancelled;
-    }
-
-    @Override
-    public void setCancelled(boolean cancel) {
-        this.cancelled = cancel;
-    }
-}

src/main/java/net/minestom/server/gamedata/loottables/ConditionedFunctionWrapper.java

@@ -22,7 +22,7 @@ public class ConditionedFunctionWrapper implements LootTableFunction {
     @Override
     public ItemStack apply(ItemStack stack, Data data) {
         for (Condition c : conditions) {
-            if(!c.test(data))
+            if (!c.test(data))
                 return stack;
         }
         return baseFunction.apply(stack, data);

src/main/java/net/minestom/server/gamedata/loottables/LootTable.java

@@ -31,10 +31,10 @@ public class LootTable {
     }
 
     public List<ItemStack> generate(Data arguments) {
-        if(arguments == null)
+        if (arguments == null)
             arguments = Data.EMPTY;
         List<ItemStack> output = new LinkedList<>();
-        for(Pool p : pools) {
+        for (Pool p : pools) {
             p.generate(output, arguments);
         }
         return output;
@@ -74,18 +74,18 @@ public class LootTable {
         }
 
         public void generate(List<ItemStack> output, Data arguments) {
-            for(Condition c : conditions) {
+            for (Condition c : conditions) {
-                if(!c.test(arguments))
+                if (!c.test(arguments))
                     return;
             }
             Random rng = new Random();
             int luck = arguments.getOrDefault(LUCK_KEY, 0);
-            int rollCount = rng.nextInt(maxRollCount - minRollCount +1 /*inclusive*/) + minRollCount;
+            int rollCount = rng.nextInt(maxRollCount - minRollCount + 1 /*inclusive*/) + minRollCount;
-            int bonusRollCount = rng.nextInt(bonusMaxRollCount - bonusMinRollCount +1 /*inclusive*/) + bonusMinRollCount;
+            int bonusRollCount = rng.nextInt(bonusMaxRollCount - bonusMinRollCount + 1 /*inclusive*/) + bonusMinRollCount;
             bonusRollCount *= luck;
             // TODO: implement luck (quality/weight) weight=floor( weight + (quality * generic.luck))
             WeightedRandom<Entry> weightedRandom = new WeightedRandom<>(entries);
-            for (int i = 0; i < rollCount+bonusRollCount; i++) {
+            for (int i = 0; i < rollCount + bonusRollCount; i++) {
                 Entry entry = weightedRandom.get(rng);
                 entry.generateStacks(output, arguments);
             }
@@ -122,8 +122,8 @@ public class LootTable {
         }
 
         public final void generateStacks(List<ItemStack> output, Data arguments) {
-            for(Condition c : conditions) {
+            for (Condition c : conditions) {
-                if(!c.test(arguments))
+                if (!c.test(arguments))
                     return;
             }
             generate(output, arguments);

src/main/java/net/minestom/server/gamedata/loottables/entries/AlternativesEntry.java

@@ -17,11 +17,11 @@ public class AlternativesEntry extends LootTable.Entry {
 
     @Override
     public void generate(List<ItemStack> output, Data arguments) {
-        for(LootTable.Entry c : children) {
+        for (LootTable.Entry c : children) {
             int previousSize = output.size();
             c.generateStacks(output, arguments);
             int newSize = output.size();
-            if(newSize != previousSize) { // an entry managed to generate, stop here
+            if (newSize != previousSize) { // an entry managed to generate, stop here
                 return;
             }
         }

src/main/java/net/minestom/server/gamedata/loottables/entries/ItemEntry.java

@@ -23,11 +23,11 @@ public class ItemEntry extends LootTable.Entry {
 
     @Override
     public void generate(List<ItemStack> output, Data arguments) {
-        ItemStack stack = new ItemStack(item, (byte)1);
+        ItemStack stack = ItemStack.of(item);
         for (LootTableFunction function : functions) {
             stack = function.apply(stack, arguments);
         }
-        if(!stack.isAir()) {
+        if (!stack.isAir()) {
             output.add(stack);
         }
     }

src/main/java/net/minestom/server/gamedata/loottables/entries/SequenceEntry.java

@@ -17,11 +17,11 @@ public class SequenceEntry extends LootTable.Entry {
 
     @Override
     public void generate(List<ItemStack> output, Data arguments) {
-        for(LootTable.Entry c : children) {
+        for (LootTable.Entry c : children) {
             int previousSize = output.size();
             c.generateStacks(output, arguments);
             int newSize = output.size();
-            if(newSize == previousSize) { // an entry failed to generate, stop here
+            if (newSize == previousSize) { // an entry failed to generate, stop here
                 return;
             }
         }

src/main/java/net/minestom/server/gamedata/loottables/entries/TagEntry.java

@@ -27,19 +27,19 @@ public class TagEntry extends LootTable.Entry {
     @Override
     public void generate(List<ItemStack> output, Data arguments) {
         Set<NamespaceID> values = tag.getValues();
-        if(values.isEmpty())
+        if (values.isEmpty())
             return;
         Material[] asArrayOfItems = new Material[values.size()];
         int ptr = 0;
         for (NamespaceID id : values) {
             asArrayOfItems[ptr++] = Registries.getMaterial(id);
         }
-        if(expand) {
+        if (expand) {
-            Material selectedItem = asArrayOfItems[rng.nextInt(asArrayOfItems.length)];
+            Material selectedMaterial = asArrayOfItems[rng.nextInt(asArrayOfItems.length)];
-            output.add(new ItemStack(selectedItem, (byte) 1));
+            output.add(ItemStack.of(selectedMaterial));
         } else {
-            for(Material item : asArrayOfItems) {
+            for (Material material : asArrayOfItems) {
-                output.add(new ItemStack(item, (byte) 1));
+                output.add(ItemStack.of(material));
             }
         }
     }

src/main/java/net/minestom/server/inventory/AbstractInventory.java

@@ -0,0 +1,223 @@
+package net.minestom.server.inventory;
+
+import net.minestom.server.data.Data;
+import net.minestom.server.data.DataContainer;
+import net.minestom.server.inventory.click.InventoryClickProcessor;
+import net.minestom.server.inventory.condition.InventoryCondition;
+import net.minestom.server.item.ItemStack;
+import net.minestom.server.utils.MathUtils;
+import net.minestom.server.utils.validate.Check;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.UnaryOperator;
+
+/**
+ * Represents an inventory where items can be modified/retrieved.
+ */
+public abstract class AbstractInventory implements InventoryClickHandler, DataContainer {
+
+    private final int size;
+    protected final ItemStack[] itemStacks;
+
+    // list of conditions/callbacks assigned to this inventory
+    protected final List<InventoryCondition> inventoryConditions = new CopyOnWriteArrayList<>();
+    // the click processor which process all the clicks in the inventory
+    protected final InventoryClickProcessor clickProcessor = new InventoryClickProcessor();
+
+    private Data data;
+
+    protected AbstractInventory(int size) {
+        this.size = size;
+        this.itemStacks = new ItemStack[getSize()];
+
+        Arrays.fill(itemStacks, ItemStack.AIR);
+    }
+
+    /**
+     * Sets an {@link ItemStack} at the specified slot and send relevant update to the viewer(s).
+     *
+     * @param slot      the slot to set the item
+     * @param itemStack the item to set
+     */
+    public synchronized void setItemStack(int slot, @NotNull ItemStack itemStack) {
+        Check.argCondition(!MathUtils.isBetween(slot, 0, getSize()),
+                "Inventory does not have the slot " + slot);
+        safeItemInsert(slot, itemStack);
+    }
+
+    protected abstract void safeItemInsert(int slot, @NotNull ItemStack itemStack);
+
+    public synchronized <T> @NotNull T processItemStack(@NotNull ItemStack itemStack,
+                                                        @NotNull TransactionType type,
+                                                        @NotNull TransactionOption<T> option) {
+        var pair = type.process(this, itemStack);
+        return option.fill(this, pair.left(), pair.right());
+    }
+
+    public synchronized <T> @NotNull List<@NotNull T> processItemStacks(@NotNull List<@NotNull ItemStack> itemStacks,
+                                                                        @NotNull TransactionType type,
+                                                                        @NotNull TransactionOption<T> option) {
+        List<T> result = new ArrayList<>(itemStacks.size());
+        itemStacks.forEach(itemStack -> {
+            T transactionResult = processItemStack(itemStack, type, option);
+            result.add(transactionResult);
+        });
+        return result;
+    }
+
+    /**
+     * Adds an {@link ItemStack} to the inventory and sends relevant update to the viewer(s).
+     *
+     * @param itemStack the item to add
+     * @param option    the transaction option
+     * @return true if the item has been successfully added, false otherwise
+     */
+    public <T> @NotNull T addItemStack(@NotNull ItemStack itemStack, @NotNull TransactionOption<T> option) {
+        return processItemStack(itemStack, TransactionType.ADD, option);
+    }
+
+    public boolean addItemStack(@NotNull ItemStack itemStack) {
+        return addItemStack(itemStack, TransactionOption.ALL_OR_NOTHING);
+    }
+
+    /**
+     * Adds {@link ItemStack}s to the inventory and sends relevant updates to the viewer(s).
+     *
+     * @param itemStacks items to add
+     * @param option     the transaction option
+     * @return the operation results
+     */
+    public <T> @NotNull List<@NotNull T> addItemStacks(@NotNull List<@NotNull ItemStack> itemStacks,
+                                                       @NotNull TransactionOption<T> option) {
+        return processItemStacks(itemStacks, TransactionType.ADD, option);
+    }
+
+    /**
+     * Takes an {@link ItemStack} from the inventory and sends relevant update to the viewer(s).
+     *
+     * @param itemStack the item to take
+     * @return true if the item has been successfully fully taken, false otherwise
+     */
+    public <T> @NotNull T takeItemStack(@NotNull ItemStack itemStack, @NotNull TransactionOption<T> option) {
+        return processItemStack(itemStack, TransactionType.TAKE, option);
+    }
+
+    /**
+     * Takes {@link ItemStack}s from the inventory and sends relevant updates to the viewer(s).
+     *
+     * @param itemStacks items to take
+     * @return the operation results
+     */
+    public <T> @NotNull List<@NotNull T> takeItemStacks(@NotNull List<@NotNull ItemStack> itemStacks,
+                                                        @NotNull TransactionOption<T> option) {
+        return processItemStacks(itemStacks, TransactionType.TAKE, option);
+    }
+
+    public synchronized void replaceItemStack(int slot, @NotNull UnaryOperator<@NotNull ItemStack> operator) {
+        var currentItem = getItemStack(slot);
+        setItemStack(slot, operator.apply(currentItem));
+    }
+
+    /**
+     * Clears the inventory and send relevant update to the viewer(s).
+     */
+    public synchronized void clear() {
+        // Clear the item array
+        Arrays.fill(itemStacks, ItemStack.AIR);
+        // Send the cleared inventory to viewers
+        update();
+    }
+
+    public abstract void update();
+
+    /**
+     * Gets the {@link ItemStack} at the specified slot.
+     *
+     * @param slot the slot to check
+     * @return the item in the slot {@code slot}
+     */
+    public @NotNull ItemStack getItemStack(int slot) {
+        return itemStacks[slot];
+    }
+
+    /**
+     * Gets all the {@link ItemStack} in the inventory.
+     * <p>
+     * Be aware that the returned array does not need to be the original one,
+     * meaning that modifying it directly may not work.
+     *
+     * @return an array containing all the inventory's items
+     */
+    public @NotNull ItemStack[] getItemStacks() {
+        return itemStacks.clone();
+    }
+
+    /**
+     * Gets the size of the inventory.
+     *
+     * @return the inventory's size
+     */
+    public int getSize() {
+        return size;
+    }
+
+    /**
+     * Gets the size of the "inner inventory" (which includes only "usable" slots).
+     *
+     * @return inner inventory's size
+     */
+    public int getInnerSize() {
+        return getSize();
+    }
+
+    /**
+     * Gets all the {@link InventoryCondition} of this inventory.
+     *
+     * @return a modifiable {@link List} containing all the inventory conditions
+     */
+    public @NotNull List<@NotNull InventoryCondition> getInventoryConditions() {
+        return inventoryConditions;
+    }
+
+    /**
+     * Adds a new {@link InventoryCondition} to this inventory.
+     *
+     * @param inventoryCondition the inventory condition to add
+     */
+    public void addInventoryCondition(@NotNull InventoryCondition inventoryCondition) {
+        this.inventoryConditions.add(inventoryCondition);
+    }
+
+    /**
+     * Places all the items of {@code itemStacks} into the internal array.
+     *
+     * @param itemStacks the array to copy the content from
+     * @throws IllegalArgumentException if the size of the array is not equal to {@link #getSize()}
+     * @throws NullPointerException     if {@code itemStacks} contains one null element or more
+     */
+    public void copyContents(@NotNull ItemStack[] itemStacks) {
+        Check.argCondition(itemStacks.length != getSize(),
+                "The size of the array has to be of the same size as the inventory: " + getSize());
+
+        for (int i = 0; i < itemStacks.length; i++) {
+            final ItemStack itemStack = itemStacks[i];
+            Check.notNull(itemStack, "The item array cannot contain any null element!");
+            setItemStack(i, itemStack);
+        }
+    }
+
+    @Override
+    public @Nullable Data getData() {
+        return data;
+    }
+
+    @Override
+    public void setData(@Nullable Data data) {
+        this.data = data;
+    }
+}

src/main/java/net/minestom/server/inventory/Inventory.java

@@ -1,33 +1,23 @@
 package net.minestom.server.inventory;
 
+import net.kyori.adventure.text.Component;
 import net.minestom.server.Viewable;
-import net.minestom.server.data.Data;
-import net.minestom.server.data.DataContainer;
 import net.minestom.server.entity.Player;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickLoopHandler;
-import net.minestom.server.inventory.click.InventoryClickProcessor;
 import net.minestom.server.inventory.click.InventoryClickResult;
-import net.minestom.server.inventory.condition.InventoryCondition;
 import net.minestom.server.item.ItemStack;
-import net.minestom.server.item.StackingRule;
 import net.minestom.server.network.packet.server.play.OpenWindowPacket;
 import net.minestom.server.network.packet.server.play.SetSlotPacket;
 import net.minestom.server.network.packet.server.play.WindowItemsPacket;
 import net.minestom.server.network.packet.server.play.WindowPropertyPacket;
 import net.minestom.server.network.player.PlayerConnection;
-import net.minestom.server.utils.ArrayUtils;
-import net.minestom.server.utils.MathUtils;
 import net.minestom.server.utils.inventory.PlayerInventoryUtils;
-import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 import java.util.Collections;
-import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -37,7 +27,7 @@ import java.util.concurrent.atomic.AtomicInteger;
  * You can create one with {@link Inventory#Inventory(InventoryType, String)} or by making your own subclass.
  * It can then be opened using {@link Player#openInventory(Inventory)}.
  */
-public class Inventory implements InventoryModifier, InventoryClickHandler, Viewable, DataContainer {
+public class Inventory extends AbstractInventory implements Viewable {
 
     // incremented each time an inventory is created (used in the window packets)
     private static final AtomicInteger LAST_INVENTORY_ID = new AtomicInteger();
@@ -46,41 +36,32 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
     private final byte id;
     // the type of this inventory
     private final InventoryType inventoryType;
-    // the title of this inventory)
+    // the title of this inventory
-    private String title;
+    private Component title;
-
-    // the size based on the inventory type
-    private final int size;
 
     private final int offset;
 
-    // the items in this inventory
-    private final ItemStack[] itemStacks;
     // the players currently viewing this inventory
     private final Set<Player> viewers = new CopyOnWriteArraySet<>();
     private final Set<Player> unmodifiableViewers = Collections.unmodifiableSet(viewers);
     // (player -> cursor item) map, used by the click listeners
     private final ConcurrentHashMap<Player, ItemStack> cursorPlayersItem = new ConcurrentHashMap<>();
 
-    // list of conditions/callbacks assigned to this inventory
+    public Inventory(@NotNull InventoryType inventoryType, @NotNull Component title) {
-    private final List<InventoryCondition> inventoryConditions = new CopyOnWriteArrayList<>();
+        super(inventoryType.getSize());
-    // the click processor which process all the clicks in the inventory
-    private final InventoryClickProcessor clickProcessor = new InventoryClickProcessor();
-
-    private Data data;
-
-    public Inventory(@NotNull InventoryType inventoryType, @NotNull String title) {
         this.id = generateId();
         this.inventoryType = inventoryType;
         this.title = title;
 
-        this.size = inventoryType.getSize();
+        this.offset = getSize();
+    }
 
-        this.offset = size;
+    /**
-
+     * @deprecated use {@link Inventory#Inventory(InventoryType, Component)}
-        this.itemStacks = new ItemStack[size];
+     */
-
+    @Deprecated
-        ArrayUtils.fill(itemStacks, ItemStack::getAirItem);
+    public Inventory(@NotNull InventoryType inventoryType, @NotNull String title) {
+        this(inventoryType, Component.text(title));
     }
 
     private static byte generateId() {
@@ -106,7 +87,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
      * @return the inventory title
      */
     @NotNull
-    public String getTitle() {
+    public Component getTitle() {
         return title;
     }
 
@@ -115,7 +96,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
      *
      * @param title the new inventory title
      */
-    public void setTitle(@NotNull String title) {
+    public void setTitle(@NotNull Component title) {
         this.title = title;
 
         OpenWindowPacket packet = new OpenWindowPacket(title);
@@ -141,85 +122,17 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
     }
 
     @Override
-    public void setItemStack(int slot, @NotNull ItemStack itemStack) {
+    public synchronized void clear() {
-        Check.argCondition(!MathUtils.isBetween(slot, 0, getSize()),
+        super.clear();
-                inventoryType.toString() + " does not have slot " + slot);
+        // Clear cursor
-
+        getViewers().forEach(player ->
-        safeItemInsert(slot, itemStack);
+                setCursorItem(player, ItemStack.AIR));
-    }
-
-    @Override
-    public synchronized boolean addItemStack(@NotNull ItemStack itemStack) {
-        final StackingRule stackingRule = itemStack.getStackingRule();
-        for (int i = 0; i < getSize(); i++) {
-            ItemStack item = getItemStack(i);
-            final StackingRule itemStackingRule = item.getStackingRule();
-            if (itemStackingRule.canBeStacked(itemStack, item)) {
-                final int itemAmount = itemStackingRule.getAmount(item);
-                if (itemAmount == stackingRule.getMaxSize())
-                    continue;
-                final int itemStackAmount = itemStackingRule.getAmount(itemStack);
-                final int totalAmount = itemStackAmount + itemAmount;
-                if (!stackingRule.canApply(itemStack, totalAmount)) {
-                    item = itemStackingRule.apply(item, itemStackingRule.getMaxSize());
-
-                    sendSlotRefresh((short) i, item);
-                    itemStack = stackingRule.apply(itemStack, totalAmount - stackingRule.getMaxSize());
-                } else {
-                    item.setAmount((byte) totalAmount);
-                    sendSlotRefresh((short) i, item);
-                    return true;
-                }
-            } else if (item.isAir()) {
-                setItemStack(i, itemStack);
-                return true;
-            }
-        }
-        return false;
-    }
-
-    @Override
-    public void clear() {
-        // Clear the item array
-        for (int i = 0; i < getSize(); i++) {
-            setItemStackInternal(i, ItemStack.getAirItem());
-        }
-        // Send the cleared inventory to viewers
-        update();
-    }
-
-
-    @NotNull
-    @Override
-    public ItemStack getItemStack(int slot) {
-        return itemStacks[slot];
-    }
-
-    @NotNull
-    @Override
-    public ItemStack[] getItemStacks() {
-        return itemStacks.clone();
-    }
-
-    @Override
-    public int getSize() {
-        return size;
-    }
-
-    @NotNull
-    @Override
-    public List<InventoryCondition> getInventoryConditions() {
-        return inventoryConditions;
-    }
-
-    @Override
-    public void addInventoryCondition(@NotNull InventoryCondition inventoryCondition) {
-        this.inventoryConditions.add(inventoryCondition);
     }
 
     /**
      * Refreshes the inventory for all viewers.
      */
+    @Override
     public void update() {
         sendPacketToViewers(createNewWindowItemsPacket());
     }
@@ -239,15 +152,6 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         playerConnection.sendPacket(createNewWindowItemsPacket());
     }
 
-    /**
-     * Refreshes only a specific slot with the updated item stack data.
-     *
-     * @param slot the slot to refresh
-     */
-    public void refreshSlot(short slot) {
-        sendSlotRefresh(slot, getItemStack(slot));
-    }
-
     @NotNull
     @Override
     public Set<Player> getViewers() {
@@ -289,7 +193,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
      */
     @NotNull
     public ItemStack getCursorItem(@NotNull Player player) {
-        return cursorPlayersItem.getOrDefault(player, ItemStack.getAirItem());
+        return cursorPlayersItem.getOrDefault(player, ItemStack.AIR);
     }
 
     /**
@@ -323,8 +227,9 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
      * @param slot      the internal slot id
      * @param itemStack the item to insert
      */
-    private synchronized void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
+    @Override
-        setItemStackInternal(slot, itemStack);
+    protected synchronized void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
+        this.itemStacks[slot] = itemStack;
         SetSlotPacket setSlotPacket = new SetSlotPacket();
         setSlotPacket.windowId = getWindowId();
         setSlotPacket.slot = (short) slot;
@@ -332,19 +237,6 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         sendPacketToViewers(setSlotPacket);
     }
 
-    /**
-     * Inserts an item into the inventory without notifying viewers.
-     * <p>
-     * This will also warn the inventory that the cached window items packet is
-     * not up-to-date.
-     *
-     * @param slot      the internal slot
-     * @param itemStack the item to insert
-     */
-    protected void setItemStackInternal(int slot, @NotNull ItemStack itemStack) {
-        itemStacks[slot] = itemStack;
-    }
-
     /**
      * Creates a complete new {@link WindowItemsPacket}.
      *
@@ -381,7 +273,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
      * @param player    the player to change the cursor item
      * @param itemStack the cursor item
      */
-    private void setCursorPlayerItem(@NotNull Player player, @NotNull ItemStack itemStack) {
+    private void refreshPlayerCursorItem(@NotNull Player player, @NotNull ItemStack itemStack) {
         this.cursorPlayersItem.put(player, itemStack);
     }
 
@@ -408,7 +300,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         } else {
             playerInventory.setItemStack(clickSlot, clickResult.getClicked());
         }
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
 
         if (!clickResult.isCancel())
             callClickEvent(player, isInWindow ? this : null, slot, ClickType.LEFT_CLICK, clicked, cursor);
@@ -435,7 +327,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         } else {
             playerInventory.setItemStack(clickSlot, clickResult.getClicked());
         }
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
 
         if (!clickResult.isCancel())
             callClickEvent(player, isInWindow ? this : null, slot, ClickType.RIGHT_CLICK, clicked, cursor);
@@ -493,7 +385,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
             updateFromClick(clickResult, player);
         }
 
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
         playerInventory.update();
         update();
 
@@ -543,7 +435,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         final boolean outsideDrop = slot == -999;
         final int clickSlot = isInWindow ? slot : PlayerInventoryUtils.convertSlot(slot, offset);
         final ItemStack clicked = outsideDrop ?
-                ItemStack.getAirItem() : (isInWindow ? getItemStack(slot) : playerInventory.getItemStack(clickSlot));
+                ItemStack.AIR : (isInWindow ? getItemStack(slot) : playerInventory.getItemStack(clickSlot));
         final ItemStack cursor = getCursorItem(player);
 
         final InventoryClickResult clickResult = clickProcessor.drop(isInWindow ? this : null, player,
@@ -562,7 +454,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
             }
         }
 
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
 
         return !clickResult.isCancel();
     }
@@ -574,7 +466,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         final int clickSlot = isInWindow ? slot : PlayerInventoryUtils.convertSlot(slot, offset);
         final ItemStack clicked = slot != -999 ?
                 (isInWindow ? getItemStack(slot) : playerInventory.getItemStack(clickSlot)) :
-                ItemStack.getAirItem();
+                ItemStack.AIR;
         final ItemStack cursor = getCursorItem(player);
 
         final InventoryClickResult clickResult = clickProcessor.dragging(isInWindow ? this : null, player,
@@ -600,7 +492,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
             updateFromClick(clickResult, player);
         }
 
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
 
         return !clickResult.isCancel();
     }
@@ -629,27 +521,11 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         if (clickResult.doRefresh())
             updateFromClick(clickResult, player);
 
-        setCursorPlayerItem(player, clickResult.getCursor());
+        refreshPlayerCursorItem(player, clickResult.getCursor());
 
         return !clickResult.isCancel();
     }
 
-    /**
-     * Refresh a slot for all viewers
-     * <p>
-     * WARNING: this does not update the items in the inventory, this is only visual
-     *
-     * @param slot      the packet slot
-     * @param itemStack the item stack to set at the slot
-     */
-    private void sendSlotRefresh(short slot, ItemStack itemStack) {
-        SetSlotPacket setSlotPacket = new SetSlotPacket();
-        setSlotPacket.windowId = getWindowId();
-        setSlotPacket.slot = slot;
-        setSlotPacket.itemStack = itemStack;
-        sendPacketToViewers(setSlotPacket);
-    }
-
     /**
      * Used to update the inventory for a specific player in order to fix his cancelled actions
      *
@@ -663,15 +539,4 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
             update(player);
         }
     }
-
-    @Nullable
-    @Override
-    public Data getData() {
-        return data;
-    }
-
-    @Override
-    public void setData(@Nullable Data data) {
-        this.data = data;
-    }
 }

src/main/java/net/minestom/server/inventory/InventoryModifier.java

@@ -1,97 +0,0 @@
-package net.minestom.server.inventory;
-
-import net.minestom.server.inventory.condition.InventoryCondition;
-import net.minestom.server.item.ItemStack;
-import net.minestom.server.utils.validate.Check;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.List;
-
-/**
- * Represents an inventory where items can be modified/retrieved.
- */
-public interface InventoryModifier {
-
-    /**
-     * Sets an {@link ItemStack} at the specified slot and send relevant update to the viewer(s).
-     *
-     * @param slot      the slot to set the item
-     * @param itemStack the item to set
-     */
-    void setItemStack(int slot, @NotNull ItemStack itemStack);
-
-    /**
-     * Adds an {@link ItemStack} to the inventory and send relevant update to the viewer(s).
-     * <p>
-     * Even the item cannot be fully added, the amount of {@code itemStack} will be updated.
-     *
-     * @param itemStack the item to add
-     * @return true if the item has been successfully fully added, false otherwise
-     */
-    boolean addItemStack(@NotNull ItemStack itemStack);
-
-    /**
-     * Clears the inventory and send relevant update to the viewer(s).
-     */
-    void clear();
-
-    /**
-     * Gets the {@link ItemStack} at the specified slot.
-     *
-     * @param slot the slot to check
-     * @return the item in the slot {@code slot}
-     */
-    @NotNull
-    ItemStack getItemStack(int slot);
-
-    /**
-     * Gets all the {@link ItemStack} in the inventory.
-     * <p>
-     * Be aware that the returned array does not need to be the original one,
-     * meaning that modifying it directly may not work.
-     *
-     * @return an array containing all the inventory's items
-     */
-    @NotNull
-    ItemStack[] getItemStacks();
-
-    /**
-     * Gets the size of the inventory.
-     *
-     * @return the inventory's size
-     */
-    int getSize();
-
-    /**
-     * Gets all the {@link InventoryCondition} of this inventory.
-     *
-     * @return a modifiable {@link List} containing all the inventory conditions
-     */
-    @NotNull
-    List<InventoryCondition> getInventoryConditions();
-
-    /**
-     * Adds a new {@link InventoryCondition} to this inventory.
-     *
-     * @param inventoryCondition the inventory condition to add
-     */
-    void addInventoryCondition(@NotNull InventoryCondition inventoryCondition);
-
-    /**
-     * Places all the items of {@code itemStacks} into the internal array.
-     *
-     * @param itemStacks the array to copy the content from
-     * @throws IllegalArgumentException if the size of the array is not equal to {@link #getSize()}
-     * @throws NullPointerException     if {@code itemStacks} contains one null element or more
-     */
-    default void copyContents(@NotNull ItemStack[] itemStacks) {
-        Check.argCondition(itemStacks.length != getSize(),
-                "The size of the array has to be of the same size as the inventory: " + getSize());
-
-        for (int i = 0; i < itemStacks.length; i++) {
-            final ItemStack itemStack = itemStacks[i];
-            Check.notNull(itemStack, "The item array cannot contain any null element!");
-            setItemStack(i, itemStack);
-        }
-    }
-}

src/main/java/net/minestom/server/inventory/PlayerInventory.java

@@ -1,147 +1,60 @@
 package net.minestom.server.inventory;
 
-import net.minestom.server.data.Data;
-import net.minestom.server.data.DataContainer;
 import net.minestom.server.entity.Player;
 import net.minestom.server.event.item.ArmorEquipEvent;
-import net.minestom.server.event.player.PlayerAddItemStackEvent;
-import net.minestom.server.event.player.PlayerSetItemStackEvent;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickLoopHandler;
-import net.minestom.server.inventory.click.InventoryClickProcessor;
 import net.minestom.server.inventory.click.InventoryClickResult;
 import net.minestom.server.inventory.condition.InventoryCondition;
 import net.minestom.server.item.ItemStack;
-import net.minestom.server.item.StackingRule;
 import net.minestom.server.network.packet.server.play.EntityEquipmentPacket;
 import net.minestom.server.network.packet.server.play.SetSlotPacket;
 import net.minestom.server.network.packet.server.play.WindowItemsPacket;
-import net.minestom.server.utils.ArrayUtils;
 import net.minestom.server.utils.MathUtils;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.List;
-import java.util.concurrent.CopyOnWriteArrayList;
 
 import static net.minestom.server.utils.inventory.PlayerInventoryUtils.*;
 
 /**
  * Represents the inventory of a {@link Player}, retrieved with {@link Player#getInventory()}.
  */
-public class PlayerInventory implements InventoryModifier, InventoryClickHandler, EquipmentHandler, DataContainer {
+public class PlayerInventory extends AbstractInventory implements EquipmentHandler {
 
     public static final int INVENTORY_SIZE = 46;
+    public static final int INNER_INVENTORY_SIZE = 36;
 
     protected final Player player;
-    protected final ItemStack[] items = new ItemStack[INVENTORY_SIZE];
+    private ItemStack cursorItem = ItemStack.AIR;
-    private ItemStack cursorItem = ItemStack.getAirItem();
-
-    private final List<InventoryCondition> inventoryConditions = new CopyOnWriteArrayList<>();
-    private final InventoryClickProcessor clickProcessor = new InventoryClickProcessor();
-
-    private Data data;
 
     public PlayerInventory(@NotNull Player player) {
+        super(INVENTORY_SIZE);
         this.player = player;
-
-        ArrayUtils.fill(items, ItemStack::getAirItem);
-    }
-
-    @NotNull
-    @Override
-    public ItemStack getItemStack(int slot) {
-        return this.items[slot];
-    }
-
-    @NotNull
-    @Override
-    public ItemStack[] getItemStacks() {
-        return items.clone();
-    }
-
-    @NotNull
-    @Override
-    public List<InventoryCondition> getInventoryConditions() {
-        return inventoryConditions;
     }
 
     @Override
     public void addInventoryCondition(@NotNull InventoryCondition inventoryCondition) {
+        // fix packet slot to inventory slot conversion
         InventoryCondition condition = (p, slot, clickType, inventoryConditionResult) -> {
             final int convertedSlot = convertPlayerInventorySlot(slot, OFFSET);
             inventoryCondition.accept(p, convertedSlot, clickType, inventoryConditionResult);
         };
 
-        this.inventoryConditions.add(condition);
+        super.addInventoryCondition(condition);
     }
 
     @Override
-    public void setItemStack(int slot, @NotNull ItemStack itemStack) {
+    public synchronized void clear() {
-        PlayerSetItemStackEvent setItemStackEvent = new PlayerSetItemStackEvent(player, slot, itemStack);
+        super.clear();
-        player.callEvent(PlayerSetItemStackEvent.class, setItemStackEvent);
+        // Reset cursor
-        if (setItemStackEvent.isCancelled())
+        setCursorItem(ItemStack.AIR);
-            return;
-        slot = setItemStackEvent.getSlot();
-        itemStack = setItemStackEvent.getItemStack();
-
-        safeItemInsert(slot, itemStack);
-    }
-
-    @Override
-    public synchronized boolean addItemStack(@NotNull ItemStack itemStack) {
-        PlayerAddItemStackEvent addItemStackEvent = new PlayerAddItemStackEvent(player, itemStack);
-        player.callEvent(PlayerAddItemStackEvent.class, addItemStackEvent);
-        if (addItemStackEvent.isCancelled())
-            return false;
-
-        itemStack = addItemStackEvent.getItemStack();
-
-        final StackingRule stackingRule = itemStack.getStackingRule();
-        for (int i = 0; i < items.length - 10; i++) {
-            ItemStack item = items[i];
-            final StackingRule itemStackingRule = item.getStackingRule();
-            if (itemStackingRule.canBeStacked(itemStack, item)) {
-                final int itemAmount = itemStackingRule.getAmount(item);
-                if (itemAmount == stackingRule.getMaxSize())
-                    continue;
-                final int itemStackAmount = itemStackingRule.getAmount(itemStack);
-                final int totalAmount = itemStackAmount + itemAmount;
-                if (!stackingRule.canApply(itemStack, totalAmount)) {
-                    item = itemStackingRule.apply(item, itemStackingRule.getMaxSize());
-
-                    sendSlotRefresh((short) convertToPacketSlot(i), item);
-                    itemStack = stackingRule.apply(itemStack, totalAmount - stackingRule.getMaxSize());
-                } else {
-                    item.setAmount((byte) totalAmount);
-                    sendSlotRefresh((short) convertToPacketSlot(i), item);
-                    return true;
-                }
-            } else if (item.isAir()) {
-                safeItemInsert(i, itemStack);
-                return true;
-            }
-        }
-        return false;
-    }
-
-    @Override
-    public void clear() {
-        // Clear the item array
-        for (int i = 0; i < getSize(); i++) {
-            setItemStackInternal(i, ItemStack.getAirItem());
-        }
-        // Send the cleared inventory to the inventory's owner
-        update();
-
         // Update equipments
         this.player.sendPacketToViewersAndSelf(player.getEquipmentsPacket());
     }
 
     @Override
-    public int getSize() {
+    public int getInnerSize() {
-        return INVENTORY_SIZE;
+        return INNER_INVENTORY_SIZE;
     }
 
     @NotNull
@@ -214,20 +127,11 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
      * Refreshes the player inventory by sending a {@link WindowItemsPacket} containing all.
      * the inventory items
      */
+    @Override
     public void update() {
         player.getPlayerConnection().sendPacket(createWindowItemsPacket());
     }
 
-    /**
-     * Refreshes only a specific slot with the updated item stack data.
-     *
-     * @param slot the slot to refresh
-     */
-    public void refreshSlot(short slot) {
-        final int packetSlot = convertToPacketSlot(slot);
-        sendSlotRefresh((short) packetSlot, getItemStack(slot));
-    }
-
     /**
      * Gets the item in player cursor.
      *
@@ -261,6 +165,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
      * @throws IllegalArgumentException if the slot {@code slot} does not exist
      * @throws NullPointerException     if {@code itemStack} is null
      */
+    @Override
     protected synchronized void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
         Check.argCondition(!MathUtils.isBetween(slot, 0, getSize()),
                 "The slot " + slot + " does not exist for player");
@@ -295,7 +200,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
             }
         }
 
-        this.items[slot] = itemStack;
+        this.itemStacks[slot] = itemStack;
 
         // Sync equipment
         if (equipmentSlot != null) {
@@ -308,10 +213,6 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
         //refreshSlot((short) slot);
     }
 
-    protected void setItemStackInternal(int slot, ItemStack itemStack) {
-        items[slot] = itemStack;
-    }
-
     /**
      * Sets an item from a packet slot.
      *
@@ -319,7 +220,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
      * @param offset    offset (generally 9 to ignore armor and craft slots)
      * @param itemStack the item stack to set
      */
-    protected void setItemStack(int slot, int offset, ItemStack itemStack) {
+    protected void setItemStack(int slot, int offset, @NotNull ItemStack itemStack) {
         final int convertedSlot = convertPlayerInventorySlot(slot, offset);
         setItemStack(convertedSlot, itemStack);
     }
@@ -333,7 +234,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
      */
     protected ItemStack getItemStack(int slot, int offset) {
         final int convertedSlot = convertPlayerInventorySlot(slot, offset);
-        return this.items[convertedSlot];
+        return this.itemStacks[convertedSlot];
     }
 
     /**
@@ -359,9 +260,9 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
     private WindowItemsPacket createWindowItemsPacket() {
         ItemStack[] convertedSlots = new ItemStack[INVENTORY_SIZE];
 
-        for (int i = 0; i < items.length; i++) {
+        for (int i = 0; i < itemStacks.length; i++) {
             final int slot = convertToPacketSlot(i);
-            convertedSlots[slot] = items[i];
+            convertedSlots[slot] = itemStacks[i];
         }
 
         WindowItemsPacket windowItemsPacket = new WindowItemsPacket();
@@ -418,7 +319,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
     public boolean drop(@NotNull Player player, int mode, int slot, int button) {
         final ItemStack cursor = getCursorItem();
         final boolean outsideDrop = slot == -999;
-        final ItemStack clicked = outsideDrop ? ItemStack.getAirItem() : getItemStack(slot, OFFSET);
+        final ItemStack clicked = outsideDrop ? ItemStack.AIR : getItemStack(slot, OFFSET);
 
         final InventoryClickResult clickResult = clickProcessor.drop(null, player,
                 mode, slot, button, clicked, cursor);
@@ -441,7 +342,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
 
         final boolean hotBarClick = convertToPacketSlot(slot) < 9;
         final InventoryClickResult clickResult = clickProcessor.shiftClick(null, player, slot, clicked, cursor,
-                new InventoryClickLoopHandler(0, items.length, 1,
+                new InventoryClickLoopHandler(0, itemStacks.length, 1,
                         i -> {
                             if (hotBarClick) {
                                 return i < 9 ? i + 9 : i - 9;
@@ -492,7 +393,7 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
     @Override
     public boolean dragging(@NotNull Player player, int slot, int button) {
         final ItemStack cursor = getCursorItem();
-        final ItemStack clicked = slot != -999 ? getItemStack(slot, OFFSET) : ItemStack.getAirItem();
+        final ItemStack clicked = slot != -999 ? getItemStack(slot, OFFSET) : ItemStack.AIR;
 
         final InventoryClickResult clickResult = clickProcessor.dragging(null, player,
                 slot, button,
@@ -516,9 +417,9 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
         final ItemStack cursor = getCursorItem();
 
         final InventoryClickResult clickResult = clickProcessor.doubleClick(null, player, slot, cursor,
-                new InventoryClickLoopHandler(0, items.length, 1,
+                new InventoryClickLoopHandler(0, itemStacks.length, 1,
                         i -> i < 9 ? i + 9 : i - 9,
-                        index -> items[index],
+                        index -> itemStacks[index],
                         this::setItemStack));
 
         if (clickResult == null)
@@ -531,15 +432,4 @@ public class PlayerInventory implements InventoryModifier, InventoryClickHandler
 
         return !clickResult.isCancel();
     }
-
-    @Nullable
-    @Override
-    public Data getData() {
-        return data;
-    }
-
-    @Override
-    public void setData(@Nullable Data data) {
-        this.data = data;
-    }
 }

src/main/java/net/minestom/server/inventory/TransactionOption.java

@@ -0,0 +1,47 @@
+package net.minestom.server.inventory;
+
+import net.minestom.server.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+@FunctionalInterface
+public interface TransactionOption<T> {
+
+    /**
+     * Place as much as the item as possible.
+     * <p>
+     * The remaining, can be air.
+     */
+    TransactionOption<ItemStack> ALL = (inventory, result, itemChangesMap) -> {
+        itemChangesMap.forEach(inventory::safeItemInsert);
+        return result;
+    };
+
+    /**
+     * Only place the item if can be fully added.
+     * <p>
+     * Returns true if the item has been added, false if nothing changed.
+     */
+    TransactionOption<Boolean> ALL_OR_NOTHING = (inventory, result, itemChangesMap) -> {
+        if (result.isAir()) {
+            // Item can be fully placed inside the inventory, do so
+            itemChangesMap.forEach(inventory::safeItemInsert);
+            return true;
+        } else {
+            // Inventory cannot accept the item fully
+            return false;
+        }
+    };
+
+    /**
+     * Loop through the inventory items without changing anything.
+     * <p>
+     * Returns true if the item can be fully added, false otherwise.
+     */
+    TransactionOption<Boolean> DRY_RUN = (inventory, result, itemChangesMap) -> result.isAir();
+
+    @NotNull T fill(@NotNull AbstractInventory inventory,
+                    @NotNull ItemStack result,
+                    @NotNull Map<@NotNull Integer, @NotNull ItemStack> itemChangesMap);
+}

src/main/java/net/minestom/server/inventory/TransactionType.java

@@ -0,0 +1,102 @@
+package net.minestom.server.inventory;
+
+import it.unimi.dsi.fastutil.Pair;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import net.minestom.server.item.ItemStack;
+import net.minestom.server.item.StackingRule;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+/**
+ * Represents a type of transaction that you can apply to an {@link AbstractInventory}.
+ */
+@FunctionalInterface
+public interface TransactionType {
+
+    /**
+     * Adds an item to the inventory.
+     * Can either take an air slot or be stacked.
+     */
+    TransactionType ADD = (inventory, itemStack) -> {
+        Int2ObjectMap<ItemStack> itemChangesMap = new Int2ObjectOpenHashMap<>();
+
+        final StackingRule stackingRule = itemStack.getStackingRule();
+
+        // Check filled slot (not air)
+        for (int i = 0; i < inventory.getInnerSize(); i++) {
+            ItemStack inventoryItem = inventory.getItemStack(i);
+            if (inventoryItem.isAir()) {
+                continue;
+            }
+            if (stackingRule.canBeStacked(itemStack, inventoryItem)) {
+                final int itemAmount = stackingRule.getAmount(inventoryItem);
+                if (itemAmount == stackingRule.getMaxSize())
+                    continue;
+                final int itemStackAmount = stackingRule.getAmount(itemStack);
+                final int totalAmount = itemStackAmount + itemAmount;
+                if (!stackingRule.canApply(itemStack, totalAmount)) {
+                    // Slot cannot accept the whole item, reduce amount to 'itemStack'
+                    itemChangesMap.put(i, stackingRule.apply(inventoryItem, stackingRule.getMaxSize()));
+                    itemStack = stackingRule.apply(itemStack, totalAmount - stackingRule.getMaxSize());
+                } else {
+                    // Slot can accept the whole item
+                    itemChangesMap.put(i, stackingRule.apply(inventoryItem, totalAmount));
+                    itemStack = stackingRule.apply(itemStack, 0);
+                    break;
+                }
+            }
+        }
+
+        // Check air slot to fill
+        for (int i = 0; i < inventory.getInnerSize(); i++) {
+            ItemStack inventoryItem = inventory.getItemStack(i);
+            if (!inventoryItem.isAir()) {
+                continue;
+            }
+            // Fill the slot
+            itemChangesMap.put(i, itemStack);
+            itemStack = stackingRule.apply(itemStack, 0);
+            break;
+        }
+
+        return Pair.of(itemStack, itemChangesMap);
+    };
+
+    /**
+     * Takes an item from the inventory.
+     * Can either transform items to air or reduce their amount.
+     */
+    TransactionType TAKE = (inventory, itemStack) -> {
+        Int2ObjectMap<ItemStack> itemChangesMap = new Int2ObjectOpenHashMap<>();
+        final StackingRule stackingRule = itemStack.getStackingRule();
+        for (int i = 0; i < inventory.getInnerSize(); i++) {
+            ItemStack inventoryItem = inventory.getItemStack(i);
+            if (inventoryItem.isAir()) {
+                continue;
+            }
+            if (stackingRule.canBeStacked(itemStack, inventoryItem)) {
+                final int itemAmount = stackingRule.getAmount(inventoryItem);
+                final int itemStackAmount = stackingRule.getAmount(itemStack);
+                if (itemStackAmount < itemAmount) {
+                    itemChangesMap.put(i, stackingRule.apply(inventoryItem, itemAmount - itemStackAmount));
+                    itemStack = stackingRule.apply(itemStack, 0);
+                    break;
+                }
+                itemChangesMap.put(i, stackingRule.apply(inventoryItem, 0));
+                itemStack = stackingRule.apply(itemStack, itemStackAmount - itemAmount);
+                if (stackingRule.getAmount(itemStack) == 0) {
+                    itemStack = stackingRule.apply(itemStack, 0);
+                    break;
+                }
+            }
+        }
+
+        return Pair.of(itemStack, itemChangesMap);
+    };
+
+    @NotNull Pair<ItemStack, Map<Integer, ItemStack>> process(@NotNull AbstractInventory inventory,
+                                                              @NotNull ItemStack itemStack);
+
+}

src/main/java/net/minestom/server/inventory/click/InventoryClickProcessor.java

@@ -91,29 +91,22 @@ public class InventoryClickProcessor {
         ItemStack resultClicked;
 
         if (clickedRule.canBeStacked(clicked, cursor)) {
-            final int amount = clicked.getAmount() + 1;
+            final int amount = clickedRule.getAmount(clicked) + 1;
             if (!clickedRule.canApply(clicked, amount)) {
                 return clickResult;
             } else {
-                resultCursor = cursorRule.apply(cursor, cursorRule.getAmount(cursor) - 1);
+                resultCursor = cursorRule.apply(cursor, operand -> operand - 1);
                 resultClicked = clickedRule.apply(clicked, amount);
             }
         } else {
             if (cursor.isAir()) {
-                final int amount = (int) Math.ceil((double) clicked.getAmount() / 2d);
+                final int amount = (int) Math.ceil((double) clickedRule.getAmount(clicked) / 2d);
-                resultCursor = clicked.clone();
+                resultCursor = cursorRule.apply(clicked, amount);
-                resultCursor = cursorRule.apply(resultCursor, amount);
+                resultClicked = clickedRule.apply(clicked, operand -> operand / 2);
-
-                resultClicked = clicked.clone();
-                resultClicked = clickedRule.apply(resultClicked, clicked.getAmount() / 2);
             } else {
                 if (clicked.isAir()) {
-                    final int amount = cursor.getAmount();
+                    resultCursor = cursorRule.apply(cursor, operand -> operand - 1);
-                    resultCursor = cursor.clone();
+                    resultClicked = clickedRule.apply(cursor, 1);
-                    resultCursor = cursorRule.apply(resultCursor, amount - 1);
-
-                    resultClicked = cursor.clone();
-                    resultClicked = clickedRule.apply(resultClicked, 1);
                 } else {
                     resultCursor = clicked;
                     resultClicked = cursor;
@@ -155,11 +148,11 @@ public class InventoryClickProcessor {
         if (clicked.isAir()) {
             // Set held item [key] to slot
             resultClicked = cursor;
-            resultHeld = ItemStack.getAirItem();
+            resultHeld = ItemStack.AIR;
         } else {
             if (cursor.isAir()) {
                 // if held item [key] is air then set clicked to held
-                resultClicked = ItemStack.getAirItem();
+                resultClicked = ItemStack.AIR;
             } else {
                 // Otherwise replace held item and held
                 resultClicked = cursor;
@@ -189,7 +182,7 @@ public class InventoryClickProcessor {
         final StackingRule clickedRule = clicked.getStackingRule();
 
         boolean filled = false;
-        ItemStack resultClicked = clicked.clone();
+        ItemStack resultClicked = clicked;
 
         for (InventoryClickLoopHandler loopHandler : loopHandlers) {
             final Int2IntFunction indexModifier = loopHandler.getIndexModifier();
@@ -242,7 +235,7 @@ public class InventoryClickProcessor {
 
                     // Switch
                     itemSetter.accept(index, resultClicked);
-                    itemSetter.accept(slot, ItemStack.getAirItem());
+                    itemSetter.accept(slot, ItemStack.AIR);
                     filled = true;
                     break;
                 }
@@ -287,16 +280,16 @@ public class InventoryClickProcessor {
                 int finalCursorAmount = cursorAmount;
 
                 for (int s : slots) {
-                    final ItemStack draggedItem = cursor.clone();
                     ItemStack slotItem = itemGetter.apply(s);
 
                     clickResult = startCondition(inventory, player, s, ClickType.DRAGGING, slotItem, cursor);
                     if (clickResult.isCancel())
                         break;
+                    StackingRule slotItemRule = slotItem.getStackingRule();
 
                     final int maxSize = stackingRule.getMaxSize();
-                    if (stackingRule.canBeStacked(draggedItem, slotItem)) {
+                    if (stackingRule.canBeStacked(cursor, slotItem)) {
-                        final int amount = slotItem.getAmount() + slotSize;
+                        final int amount = slotItemRule.getAmount(slotItem) + slotSize;
                         if (stackingRule.canApply(slotItem, amount)) {
                             slotItem = stackingRule.apply(slotItem, amount);
                             finalCursorAmount -= slotSize;
@@ -306,7 +299,7 @@ public class InventoryClickProcessor {
                             finalCursorAmount -= removedAmount;
                         }
                     } else if (slotItem.isAir()) {
-                        slotItem = stackingRule.apply(draggedItem, slotSize);
+                        slotItem = stackingRule.apply(cursor, slotSize);
                         finalCursorAmount -= slotSize;
                     }
                     itemSetter.accept(s, slotItem);
@@ -327,15 +320,16 @@ public class InventoryClickProcessor {
                 if (size > cursorAmount)
                     return null;
                 for (int s : slots) {
-                    ItemStack draggedItem = cursor.clone();
+                    ItemStack draggedItem = cursor;
                     ItemStack slotItem = itemGetter.apply(s);
 
                     clickResult = startCondition(inventory, player, s, ClickType.DRAGGING, slotItem, cursor);
                     if (clickResult.isCancel())
                         break;
 
+                    StackingRule slotItemRule = slotItem.getStackingRule();
                     if (stackingRule.canBeStacked(draggedItem, slotItem)) {
-                        final int amount = slotItem.getAmount() + 1;
+                        final int amount = slotItemRule.getAmount(slotItem) + 1;
                         if (stackingRule.canApply(slotItem, amount)) {
                             slotItem = stackingRule.apply(slotItem, amount);
                             itemSetter.accept(s, slotItem);
@@ -377,7 +371,7 @@ public class InventoryClickProcessor {
     @Nullable
     public InventoryClickResult doubleClick(@Nullable Inventory inventory, @NotNull Player player, int slot,
                                             @NotNull ItemStack cursor, @NotNull InventoryClickLoopHandler... loopHandlers) {
-        InventoryClickResult clickResult = startCondition(inventory, player, slot, ClickType.START_DOUBLE_CLICK, ItemStack.getAirItem(), cursor);
+        InventoryClickResult clickResult = startCondition(inventory, player, slot, ClickType.START_DOUBLE_CLICK, ItemStack.AIR, cursor);
 
         if (clickResult.isCancel()) {
             return clickResult;
@@ -446,8 +440,8 @@ public class InventoryClickProcessor {
         final StackingRule clickedRule = clicked.getStackingRule();
         final StackingRule cursorRule = cursor.getStackingRule();
 
-        ItemStack resultClicked = clicked.clone();
+        ItemStack resultClicked = clicked;
-        ItemStack resultCursor = cursor.clone();
+        ItemStack resultCursor = cursor;
 
 
         if (slot == -999) {
@@ -455,7 +449,7 @@ public class InventoryClickProcessor {
             if (button == 0) {
                 // Left (drop all)
                 final int amount = cursorRule.getAmount(resultCursor);
-                final ItemStack dropItem = cursorRule.apply(resultCursor.clone(), amount);
+                final ItemStack dropItem = cursorRule.apply(resultCursor, amount);
                 final boolean dropResult = player.dropItem(dropItem);
                 clickResult.setCancel(!dropResult);
                 if (dropResult) {
@@ -463,7 +457,7 @@ public class InventoryClickProcessor {
                 }
             } else if (button == 1) {
                 // Right (drop 1)
-                final ItemStack dropItem = cursorRule.apply(resultCursor.clone(), 1);
+                final ItemStack dropItem = cursorRule.apply(resultCursor, 1);
                 final boolean dropResult = player.dropItem(dropItem);
                 clickResult.setCancel(!dropResult);
                 if (dropResult) {
@@ -476,7 +470,7 @@ public class InventoryClickProcessor {
         } else if (mode == 4) {
             if (button == 0) {
                 // Drop key Q (drop 1)
-                final ItemStack dropItem = cursorRule.apply(resultClicked.clone(), 1);
+                final ItemStack dropItem = cursorRule.apply(resultClicked, 1);
                 final boolean dropResult = player.dropItem(dropItem);
                 clickResult.setCancel(!dropResult);
                 if (dropResult) {
@@ -487,7 +481,7 @@ public class InventoryClickProcessor {
             } else if (button == 1) {
                 // Ctrl + Drop key Q (drop all)
                 final int amount = cursorRule.getAmount(resultClicked);
-                final ItemStack dropItem = clickedRule.apply(resultClicked.clone(), amount);
+                final ItemStack dropItem = clickedRule.apply(resultClicked, amount);
                 final boolean dropResult = player.dropItem(dropItem);
                 clickResult.setCancel(!dropResult);
                 if (dropResult) {
@@ -517,7 +511,7 @@ public class InventoryClickProcessor {
 
         // Call ItemStack#onInventoryClick
         {
-            clickResult.getClicked().onInventoryClick(player, clickType, slot, isPlayerInventory);
+            //clickResult.getClicked().onInventoryClick(player, clickType, slot, isPlayerInventory);
         }
 
         // Reset the didCloseInventory field
@@ -578,6 +572,7 @@ public class InventoryClickProcessor {
                                 @NotNull ClickType clickType, @NotNull ItemStack clicked, @NotNull ItemStack cursor) {
         InventoryClickEvent inventoryClickEvent = new InventoryClickEvent(inventory, player, slot, clickType, clicked, cursor);
         player.callEvent(InventoryClickEvent.class, inventoryClickEvent);
+        System.out.println("click");
     }
 
     public void clearCache(@NotNull Player player) {

src/main/java/net/minestom/server/inventory/condition/InventoryCondition.java

@@ -1,11 +1,11 @@
 package net.minestom.server.inventory.condition;
 
 import net.minestom.server.entity.Player;
-import net.minestom.server.inventory.InventoryModifier;
+import net.minestom.server.inventory.AbstractInventory;
 import net.minestom.server.inventory.click.ClickType;
 
 /**
- * Can be added to any {@link InventoryModifier}
+ * Can be added to any {@link AbstractInventory}
  * using {@link net.minestom.server.inventory.Inventory#addInventoryCondition(InventoryCondition)}
  * or {@link net.minestom.server.inventory.PlayerInventory#addInventoryCondition(InventoryCondition)}
  * in order to listen to any issued clicks.

src/main/java/net/minestom/server/item/ItemDisplay.java

@@ -1,72 +0,0 @@
-package net.minestom.server.item;
-
-import net.kyori.adventure.text.Component;
-import net.minestom.server.chat.JsonMessage;
-
-public class ItemDisplay {
-
-    private Component displayName;
-    private Component[] lore;
-
-    /**
-     * @deprecated Use {@link #ItemDisplay(Component, Component[])}
-     */
-    @Deprecated
-    public ItemDisplay(JsonMessage displayName, JsonMessage[] lore) {
-        this.displayName = displayName.asComponent();
-        this.lore = new Component[lore.length];
-
-        for (int i = 0; i < lore.length; i++) {
-            this.lore[i] = lore[i].asComponent();
-        }
-    }
-
-    public ItemDisplay(Component displayName, Component[] lore) {
-        this.displayName = displayName;
-        this.lore = lore;
-    }
-
-    /**
-     * Gets the item display name.
-     *
-     * @return the item display name
-     * @deprecated Use {@link #getDisplayName()}
-     */
-    @Deprecated
-    public JsonMessage getDisplayNameJson() {
-        return JsonMessage.fromComponent(displayName);
-    }
-
-    /**
-     * Gets the item lore.
-     *
-     * @return the item lore
-     * @deprecated Use {@link #getLore()}
-     */
-    @Deprecated
-    public JsonMessage[] getLoreJson() {
-        JsonMessage[] loreOld = new JsonMessage[lore.length];
-        for (int i = 0; i < lore.length; i++) {
-            loreOld[i] = JsonMessage.fromComponent(lore[i]);
-        }
-        return loreOld;
-    }
-
-    /**
-     * Gets the item display name.
-     *
-     * @return the item display name
-     */
-    public Component getDisplayName() {
-        return displayName;
-    }
-
-    /**
-     * Gets the item lore.
-     *
-     * @return the item lore
-     */
-    public Component[] getLore() {
-        return lore;
-    }
-}

src/main/java/net/minestom/server/item/ItemHideFlag.java

@@ -1,9 +1,9 @@
 package net.minestom.server.item;
 
 /**
- * Represents a flag which can be applied to an {@link ItemStack} using {@link ItemStack#addItemFlags(ItemFlag...)}.
+ * Represents a hide flag which can be applied to an {@link ItemStack} using {@link ItemMetaBuilder#hideFlag(int)}.
  */
-public enum ItemFlag {
+public enum ItemHideFlag {
     HIDE_ENCHANTS(1),
     HIDE_ATTRIBUTES(2),
     HIDE_UNBREAKABLE(4),
@@ -13,7 +13,7 @@ public enum ItemFlag {
 
     private final int bitFieldPart;
 
-    ItemFlag(int bit) {
+    ItemHideFlag(int bit) {
         this.bitFieldPart = bit;
     }
 

src/main/java/net/minestom/server/item/ItemMeta.java

@@ -0,0 +1,165 @@
+package net.minestom.server.item;
+
+import net.kyori.adventure.text.Component;
+import net.minestom.server.instance.block.Block;
+import net.minestom.server.item.attribute.ItemAttribute;
+import net.minestom.server.utils.binary.BinaryWriter;
+import net.minestom.server.utils.binary.Writeable;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jglrxavpok.hephaistos.nbt.NBTCompound;
+
+import java.util.*;
+import java.util.function.Consumer;
+
+public class ItemMeta implements Writeable {
+
+    private final int damage;
+    private final boolean unbreakable;
+    private final int hideFlag;
+    private final Component displayName;
+    private final List<Component> lore;
+
+    private final Map<Enchantment, Short> enchantmentMap;
+    private final List<ItemAttribute> attributes;
+
+    private final int customModelData;
+
+    private final Set<Block> canDestroy;
+    private final Set<Block> canPlaceOn;
+
+    private final NBTCompound nbt;
+    private final ItemMetaBuilder emptyBuilder;
+
+    private String cachedSNBT;
+    private BinaryWriter cachedBuffer;
+
+    protected ItemMeta(@NotNull ItemMetaBuilder metaBuilder) {
+        this.damage = metaBuilder.damage;
+        this.unbreakable = metaBuilder.unbreakable;
+        this.hideFlag = metaBuilder.hideFlag;
+        this.displayName = metaBuilder.displayName;
+        this.lore = new ArrayList<>(metaBuilder.lore);
+        this.enchantmentMap = new HashMap<>(metaBuilder.enchantmentMap);
+        this.attributes = new ArrayList<>(metaBuilder.attributes);
+        this.customModelData = metaBuilder.customModelData;
+        this.canDestroy = new HashSet<>(metaBuilder.canDestroy);
+        this.canPlaceOn = new HashSet<>(metaBuilder.canPlaceOn);
+
+        this.nbt = metaBuilder.nbt;
+        this.emptyBuilder = metaBuilder.getSupplier().get();
+    }
+
+    @Contract(value = "_, -> new", pure = true)
+    public @NotNull ItemMeta with(@NotNull Consumer<@NotNull ItemMetaBuilder> builderConsumer) {
+        var builder = builder();
+        builderConsumer.accept(builder);
+        return builder.build();
+    }
+
+    @Contract(pure = true)
+    public int getDamage() {
+        return damage;
+    }
+
+    @Contract(pure = true)
+    public boolean isUnbreakable() {
+        return unbreakable;
+    }
+
+    @Contract(pure = true)
+    public int getHideFlag() {
+        return hideFlag;
+    }
+
+    @Contract(pure = true)
+    public @Nullable Component getDisplayName() {
+        return displayName;
+    }
+
+    @Contract(pure = true)
+    public @NotNull List<@NotNull Component> getLore() {
+        return Collections.unmodifiableList(lore);
+    }
+
+    @Contract(pure = true)
+    public @NotNull Map<Enchantment, Short> getEnchantmentMap() {
+        return Collections.unmodifiableMap(enchantmentMap);
+    }
+
+    @Contract(pure = true)
+    public @NotNull List<@NotNull ItemAttribute> getAttributes() {
+        return Collections.unmodifiableList(attributes);
+    }
+
+    @Contract(pure = true)
+    public int getCustomModelData() {
+        return customModelData;
+    }
+
+    @Contract(pure = true)
+    public @NotNull Set<@NotNull Block> getCanDestroy() {
+        return Collections.unmodifiableSet(canDestroy);
+    }
+
+    @Contract(pure = true)
+    public @NotNull Set<@NotNull Block> getCanPlaceOn() {
+        return Collections.unmodifiableSet(canPlaceOn);
+    }
+
+    @Contract(pure = true)
+    public <T> T getOrDefault(@NotNull ItemTag<T> tag, @Nullable T defaultValue) {
+        var key = tag.getKey();
+        if (nbt.containsKey(key)) {
+            return tag.read(toNBT());
+        } else {
+            return defaultValue;
+        }
+    }
+
+    public <T> @Nullable T get(@NotNull ItemTag<T> tag) {
+        return tag.read(toNBT());
+    }
+
+    public @NotNull NBTCompound toNBT() {
+        return nbt.deepClone();
+    }
+
+    public @NotNull String toSNBT() {
+        if (cachedSNBT == null) {
+            this.cachedSNBT = nbt.toSNBT();
+        }
+        return cachedSNBT;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        ItemMeta itemMeta = (ItemMeta) o;
+        return nbt.equals(itemMeta.nbt);
+    }
+
+    @Override
+    public int hashCode() {
+        return nbt.hashCode();
+    }
+
+    @Contract(value = "-> new", pure = true)
+    protected @NotNull ItemMetaBuilder builder() {
+        return ItemMetaBuilder.fromNBT(emptyBuilder, nbt);
+    }
+
+    @Override
+    public synchronized void write(@NotNull BinaryWriter writer) {
+        if (cachedBuffer == null) {
+            BinaryWriter w = new BinaryWriter();
+            w.writeNBT("", nbt);
+            this.cachedBuffer = w;
+        }
+        writer.write(cachedBuffer);
+        cachedBuffer.getBuffer().resetReaderIndex();
+    }
+}

src/main/java/net/minestom/server/item/ItemMetaBuilder.java

@@ -0,0 +1,271 @@
+package net.minestom.server.item;
+
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
+import net.minestom.server.adventure.AdventureSerializer;
+import net.minestom.server.instance.block.Block;
+import net.minestom.server.item.attribute.ItemAttribute;
+import net.minestom.server.utils.NBTUtils;
+import net.minestom.server.utils.Utils;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jglrxavpok.hephaistos.nbt.*;
+
+import java.util.*;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+public abstract class ItemMetaBuilder {
+
+    protected NBTCompound nbt = new NBTCompound();
+
+    protected int damage;
+    protected boolean unbreakable;
+    protected int hideFlag;
+    protected Component displayName;
+    protected List<Component> lore = new ArrayList<>();
+    protected Map<Enchantment, Short> enchantmentMap = new HashMap<>();
+    protected List<ItemAttribute> attributes = new ArrayList<>();
+    protected int customModelData;
+    protected Set<Block> canDestroy = new HashSet<>();
+    protected Set<Block> canPlaceOn = new HashSet<>();
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder damage(int damage) {
+        this.damage = damage;
+        this.nbt.setInt("Damage", damage);
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder unbreakable(boolean unbreakable) {
+        this.unbreakable = unbreakable;
+        this.nbt.setByte("Unbreakable", (byte) (unbreakable ? 1 : 0));
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder hideFlag(int hideFlag) {
+        this.hideFlag = hideFlag;
+        this.nbt.setInt("HideFlags", hideFlag);
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder hideFlag(@NotNull ItemHideFlag... hideFlags) {
+        int result = 0;
+        for (ItemHideFlag hideFlag : hideFlags) {
+            result |= hideFlag.getBitFieldPart();
+        }
+        return hideFlag(result);
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder displayName(@Nullable Component displayName) {
+        this.displayName = displayName;
+        handleCompound("display", nbtCompound -> {
+            if (displayName != null) {
+                final String name = AdventureSerializer.serialize(displayName);
+                nbtCompound.setString("Name", name);
+            } else {
+                nbtCompound.removeTag("Name");
+            }
+        });
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder lore(@NotNull List<@NotNull Component> lore) {
+        this.lore = lore;
+        handleCompound("display", nbtCompound -> {
+            final NBTList<NBTString> loreNBT = new NBTList<>(NBTTypes.TAG_String);
+            for (Component line : lore) {
+                loreNBT.add(new NBTString(GsonComponentSerializer.gson().serialize(line)));
+            }
+            nbtCompound.set("Lore", loreNBT);
+        });
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder lore(Component... lore) {
+        lore(Arrays.asList(lore));
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder enchantments(@NotNull Map<Enchantment, Short> enchantments) {
+        this.enchantmentMap = enchantments;
+        handleMap(enchantmentMap, "Enchantments", nbt, () -> {
+            NBTUtils.writeEnchant(nbt, "Enchantments", enchantmentMap);
+            return nbt.get("Enchantments");
+        });
+        return this;
+    }
+
+    @Contract("_, _ -> this")
+    public @NotNull ItemMetaBuilder enchantment(@NotNull Enchantment enchantment, short level) {
+        this.enchantmentMap.put(enchantment, level);
+        enchantments(enchantmentMap);
+        return this;
+    }
+
+    @Contract("-> this")
+    public @NotNull ItemMetaBuilder clearEnchantment() {
+        this.enchantmentMap.clear();
+        enchantments(enchantmentMap);
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder attributes(@NotNull List<@NotNull ItemAttribute> attributes) {
+        this.attributes = attributes;
+
+        handleCollection(attributes, "AttributeModifiers", nbt, () -> {
+            NBTList<NBTCompound> attributesNBT = new NBTList<>(NBTTypes.TAG_Compound);
+            for (ItemAttribute itemAttribute : attributes) {
+                final UUID uuid = itemAttribute.getUuid();
+                attributesNBT.add(
+                        new NBTCompound()
+                                .setIntArray("UUID", Utils.uuidToIntArray(uuid))
+                                .setDouble("Amount", itemAttribute.getValue())
+                                .setString("Slot", itemAttribute.getSlot().name().toLowerCase())
+                                .setString("AttributeName", itemAttribute.getAttribute().getKey())
+                                .setInt("Operation", itemAttribute.getOperation().getId())
+                                .setString("Name", itemAttribute.getInternalName())
+                );
+            }
+            return attributesNBT;
+        });
+
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder customModelData(int customModelData) {
+        this.customModelData = customModelData;
+        this.nbt.setInt("CustomModelData", customModelData);
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder canPlaceOn(@NotNull Set<@NotNull Block> blocks) {
+        this.canPlaceOn = blocks;
+        handleCollection(canPlaceOn, "CanPlaceOn", nbt, () -> {
+            NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
+            canPlaceOn.forEach(block -> list.add(new NBTString(block.getName())));
+            nbt.set("CanPlaceOn", list);
+            return list;
+        });
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder canPlaceOn(@NotNull Block... blocks) {
+        return canPlaceOn(Set.of(blocks));
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder canDestroy(@NotNull Set<@NotNull Block> blocks) {
+        this.canDestroy = blocks;
+        handleCollection(canDestroy, "CanDestroy", nbt, () -> {
+            NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
+            canDestroy.forEach(block -> list.add(new NBTString(block.getName())));
+            nbt.set("CanDestroy", list);
+            return list;
+        });
+        return this;
+    }
+
+    @Contract("_ -> this")
+    public @NotNull ItemMetaBuilder canDestroy(@NotNull Block... blocks) {
+        return canDestroy(Set.of(blocks));
+    }
+
+    public <T> @NotNull ItemMetaBuilder set(@NotNull ItemTag<T> tag, @Nullable T value) {
+        if (value != null) {
+            tag.write(nbt, value);
+        } else {
+            this.nbt.removeTag(tag.getKey());
+        }
+        return this;
+    }
+
+    @Contract("-> new")
+    public abstract @NotNull ItemMeta build();
+
+    public abstract void read(@NotNull NBTCompound nbtCompound);
+
+    protected abstract @NotNull Supplier<@NotNull ItemMetaBuilder> getSupplier();
+
+    protected void handleCompound(@NotNull String key,
+                                  @NotNull Consumer<@NotNull NBTCompound> consumer) {
+        NBTCompound compound = null;
+        boolean newNbt = false;
+        if (nbt.containsKey(key)) {
+            NBT dNbt = nbt.get(key);
+            if (dNbt instanceof NBTCompound) {
+                compound = (NBTCompound) dNbt;
+            }
+        } else {
+            compound = new NBTCompound();
+            newNbt = true;
+        }
+
+        if (compound != null) {
+            consumer.accept(compound);
+
+            if (newNbt && compound.getSize() > 0) {
+                this.nbt.set(key, compound);
+            } else if (!newNbt && compound.getSize() == 0) {
+                this.nbt.removeTag(key);
+            }
+
+        }
+    }
+
+    protected void handleNullable(@Nullable Object value,
+                                  @NotNull String key,
+                                  @NotNull NBTCompound nbtCompound,
+                                  @NotNull Supplier<@NotNull NBT> supplier) {
+        if (value != null) {
+            nbtCompound.set(key, supplier.get());
+        } else {
+            nbtCompound.removeTag(key);
+        }
+    }
+
+    protected void handleCollection(@NotNull Collection<?> objects,
+                                    @NotNull String key,
+                                    @NotNull NBTCompound nbtCompound,
+                                    @NotNull Supplier<@NotNull NBT> supplier) {
+        if (!objects.isEmpty()) {
+            nbtCompound.set(key, supplier.get());
+        } else {
+            nbtCompound.removeTag(key);
+        }
+    }
+
+    protected void handleMap(@NotNull Map<?, ?> objects,
+                             @NotNull String key,
+                             @NotNull NBTCompound nbtCompound,
+                             @NotNull Supplier<@NotNull NBT> supplier) {
+        if (!objects.isEmpty()) {
+            nbtCompound.set(key, supplier.get());
+        } else {
+            nbtCompound.removeTag(key);
+        }
+    }
+
+    @Contract(value = "_, _ -> new", pure = true)
+    public static @NotNull ItemMetaBuilder fromNBT(@NotNull ItemMetaBuilder src, @NotNull NBTCompound nbtCompound) {
+        ItemMetaBuilder dest = src.getSupplier().get();
+        NBTUtils.loadDataIntoMeta(dest, nbtCompound);
+        return dest;
+    }
+
+    public interface Provider<T extends ItemMetaBuilder> {
+    }
+
+}

src/main/java/net/minestom/server/item/ItemStackBuilder.java

@@ -0,0 +1,122 @@
+package net.minestom.server.item;
+
+import net.kyori.adventure.text.Component;
+import net.minestom.server.item.metadata.*;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jglrxavpok.hephaistos.nbt.NBTCompound;
+
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+import java.util.function.UnaryOperator;
+
+public class ItemStackBuilder {
+
+    private final Material material;
+    private int amount;
+    protected ItemMetaBuilder metaBuilder;
+
+    protected ItemStackBuilder(@NotNull Material material, @NotNull ItemMetaBuilder metaBuilder) {
+        this.material = material;
+        this.amount = 1;
+        this.metaBuilder = metaBuilder;
+    }
+
+    private static final Map<Material, Supplier<ItemMetaBuilder>> MATERIAL_SUPPLIER_MAP = new ConcurrentHashMap<>();
+
+    static {
+        MATERIAL_SUPPLIER_MAP.put(Material.POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LINGERING_POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.SPLASH_POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.TIPPED_ARROW, PotionMeta.Builder::new);
+
+        MATERIAL_SUPPLIER_MAP.put(Material.FILLED_MAP, MapMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.COMPASS, CompassMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.ENCHANTED_BOOK, EnchantedBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.CROSSBOW, CrossbowMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.WRITABLE_BOOK, WritableBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.WRITTEN_BOOK, WrittenBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.FIREWORK_STAR, FireworkEffectMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.FIREWORK_ROCKET, FireworkMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.PLAYER_HEAD, PlayerHeadMeta.Builder::new);
+
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_HELMET, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_CHESTPLATE, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_LEGGINGS, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_BOOTS, LeatherArmorMeta.Builder::new);
+    }
+
+    protected ItemStackBuilder(@NotNull Material material) {
+        this(material,
+                MATERIAL_SUPPLIER_MAP.getOrDefault(material, DefaultMeta::new).get());
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder amount(int amount) {
+        this.amount = amount;
+        return this;
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder meta(@NotNull ItemMeta itemMeta) {
+        this.metaBuilder = itemMeta.builder();
+        return this;
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder meta(@NotNull UnaryOperator<@NotNull ItemMetaBuilder> itemMetaConsumer) {
+        this.metaBuilder = itemMetaConsumer.apply(metaBuilder);
+        return this;
+    }
+
+    @Contract(value = "_, _ -> this")
+    public <T extends ItemMetaBuilder, U extends ItemMetaBuilder.Provider<T>> @NotNull ItemStackBuilder meta(@NotNull Class<U> metaType, @NotNull Consumer<@NotNull T> itemMetaConsumer) {
+        itemMetaConsumer.accept((T) metaBuilder);
+        return this;
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder displayName(@Nullable Component displayName) {
+        this.metaBuilder.displayName(displayName);
+        return this;
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder lore(@NotNull List<@NotNull Component> lore) {
+        this.metaBuilder.lore(lore);
+        return this;
+    }
+
+    @Contract(value = "_ -> this")
+    public @NotNull ItemStackBuilder lore(Component... lore) {
+        this.metaBuilder.lore(lore);
+        return this;
+    }
+
+    @Contract(value = "-> new", pure = true)
+    public @NotNull ItemStack build() {
+        return new ItemStack(material, amount, metaBuilder.build());
+    }
+
+    private static final class DefaultMeta extends ItemMetaBuilder {
+        @Override
+        public @NotNull ItemMeta build() {
+            return new ItemMeta(this);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            // Empty
+        }
+
+        @Override
+        protected @NotNull Supplier<@NotNull ItemMetaBuilder> getSupplier() {
+            return DefaultMeta::new;
+        }
+    }
+
+}

src/main/java/net/minestom/server/item/ItemTag.java

@@ -0,0 +1,97 @@
+package net.minestom.server.item;
+
+import org.jetbrains.annotations.NotNull;
+import org.jglrxavpok.hephaistos.nbt.NBTCompound;
+
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+
+public class ItemTag<T> {
+
+    private final String key;
+    private final Function<NBTCompound, T> readFunction;
+    private final BiConsumer<NBTCompound, T> writeConsumer;
+
+    private ItemTag(@NotNull String key,
+                    @NotNull Function<NBTCompound, T> readFunction,
+                    @NotNull BiConsumer<NBTCompound, T> writeConsumer) {
+        this.key = key;
+        this.readFunction = readFunction;
+        this.writeConsumer = writeConsumer;
+    }
+
+    public @NotNull String getKey() {
+        return key;
+    }
+
+    protected T read(@NotNull NBTCompound nbtCompound) {
+        return readFunction.apply(nbtCompound);
+    }
+
+    protected void write(@NotNull NBTCompound nbtCompound, @NotNull T value) {
+        this.writeConsumer.accept(nbtCompound, value);
+    }
+
+    public static @NotNull ItemTag<Byte> Byte(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getByte(key),
+                (nbtCompound, value) -> nbtCompound.setByte(key, value));
+    }
+
+    public static @NotNull ItemTag<Short> Short(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getShort(key),
+                (nbtCompound, value) -> nbtCompound.setShort(key, value));
+    }
+
+    public static @NotNull ItemTag<Integer> Integer(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getInt(key),
+                (nbtCompound, integer) -> nbtCompound.setInt(key, integer));
+    }
+
+    public static @NotNull ItemTag<Long> Long(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getLong(key),
+                (nbtCompound, value) -> nbtCompound.setLong(key, value));
+    }
+
+    public static @NotNull ItemTag<Float> Float(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getFloat(key),
+                (nbtCompound, value) -> nbtCompound.setFloat(key, value));
+    }
+
+    public static @NotNull ItemTag<Double> Double(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getDouble(key),
+                (nbtCompound, value) -> nbtCompound.setDouble(key, value));
+    }
+
+    public static @NotNull ItemTag<byte[]> ByteArray(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getByteArray(key),
+                (nbtCompound, value) -> nbtCompound.setByteArray(key, value));
+    }
+
+    public static @NotNull ItemTag<String> String(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getString(key),
+                (nbtCompound, value) -> nbtCompound.setString(key, value));
+    }
+
+    // TODO List/Compound
+
+    public static @NotNull ItemTag<int[]> IntArray(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getIntArray(key),
+                (nbtCompound, value) -> nbtCompound.setIntArray(key, value));
+    }
+
+    public static @NotNull ItemTag<long[]> LongArray(@NotNull String key) {
+        return new ItemTag<>(key,
+                nbtCompound -> nbtCompound.getLongArray(key),
+                (nbtCompound, value) -> nbtCompound.setLongArray(key, value));
+    }
+
+}

src/main/java/net/minestom/server/item/StackingRule.java

@@ -1,7 +1,10 @@
 package net.minestom.server.item;
 
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.function.IntUnaryOperator;
+
 /**
  * Represents the stacking rule of an {@link ItemStack}.
  * This can be used to mimic the vanilla one (using the displayed item quantity)
@@ -40,10 +43,15 @@ public abstract class StackingRule {
      *
      * @param item      the {@link ItemStack} to applies the size to
      * @param newAmount the new item size
-     * @return the new {@link ItemStack} with the new amount
+     * @return a new {@link ItemStack item} with the specified amount
      */
-    @NotNull
+    @Contract("_, _ -> new")
-    public abstract ItemStack apply(@NotNull ItemStack item, int newAmount);
+    public abstract @NotNull ItemStack apply(@NotNull ItemStack item, int newAmount);
+
+    @Contract("_, _ -> new")
+    public @NotNull ItemStack apply(@NotNull ItemStack item, @NotNull IntUnaryOperator amountOperator) {
+        return apply(item, amountOperator.applyAsInt(getAmount(item)));
+    }
 
     /**
      * Used to determine the current stack size of an {@link ItemStack}.

src/main/java/net/minestom/server/item/metadata/CompassMeta.java

@@ -1,103 +1,107 @@
 package net.minestom.server.item.metadata;
 
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.utils.Position;
-import net.minestom.server.utils.clone.CloneUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
-import java.util.Objects;
+import java.util.function.Supplier;
 
-public class CompassMeta extends ItemMeta {
+public class CompassMeta extends ItemMeta implements ItemMetaBuilder.Provider<CompassMeta.Builder> {
 
-    private boolean lodestoneTracked;
+    private final boolean lodestoneTracked;
-    private String lodestoneDimension;
+    private final String lodestoneDimension;
+    private final Position lodestonePosition;
 
-    private Position lodestonePosition;
+    protected CompassMeta(ItemMetaBuilder metaBuilder,
+                          boolean lodestoneTracked,
+                          @Nullable String lodestoneDimension,
+                          @Nullable Position lodestonePosition) {
+        super(metaBuilder);
+        this.lodestoneTracked = lodestoneTracked;
+        this.lodestoneDimension = lodestoneDimension;
+        this.lodestonePosition = lodestonePosition;
+    }
 
     public boolean isLodestoneTracked() {
         return lodestoneTracked;
     }
 
-    public void setLodestoneTracked(boolean lodestoneTracked) {
+    public @Nullable String getLodestoneDimension() {
-        this.lodestoneTracked = lodestoneTracked;
-    }
-
-    @Nullable
-    public String getLodestoneDimension() {
         return lodestoneDimension;
     }
 
-    public void setLodestoneDimension(@Nullable String lodestoneDimension) {
+    public @Nullable Position getLodestonePosition() {
-        this.lodestoneDimension = lodestoneDimension;
-    }
-
-    @Nullable
-    public Position getLodestonePosition() {
         return lodestonePosition;
     }
 
-    public void setLodestonePosition(@Nullable Position lodestonePosition) {
+    public static class Builder extends ItemMetaBuilder {
-        this.lodestonePosition = lodestonePosition;
-    }
 
-    @Override
+        private boolean lodestoneTracked;
-    public boolean hasNbt() {
+        private String lodestoneDimension;
-        return true;
+        private Position lodestonePosition;
-    }
 
-    @Override
+        public Builder lodestoneTracked(boolean lodestoneTracked) {
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+            this.lodestoneTracked = lodestoneTracked;
-        if (!(itemMeta instanceof CompassMeta))
+            this.nbt.setByte("LodestoneTracked", (byte) (lodestoneTracked ? 1 : 0));
-            return false;
+            return this;
-        CompassMeta compassMeta = (CompassMeta) itemMeta;
-        return (compassMeta.lodestoneTracked == lodestoneTracked) &&
-                (Objects.equals(compassMeta.lodestoneDimension, lodestoneDimension)) &&
-                (Objects.equals(compassMeta.lodestonePosition, lodestonePosition));
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("LodestoneTracked")) {
-            this.lodestoneTracked = compound.getByte("LodestoneTracked") == 1;
-        }
-        if (compound.containsKey("LodestoneDimension")) {
-            this.lodestoneDimension = compound.getString("LodestoneDimension");
-        }
-        if (compound.containsKey("LodestonePos")) {
-            final NBTCompound posCompound = compound.getCompound("LodestonePos");
-            final int x = posCompound.getInt("X");
-            final int y = posCompound.getInt("Y");
-            final int z = posCompound.getInt("Z");
-
-            this.lodestonePosition = new Position(x, y, z);
-        }
-    }
-
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        compound.setByte("LodestoneTracked", (byte) (lodestoneTracked ? 1 : 0));
-        if (lodestoneDimension != null) {
-            compound.setString("LodestoneDimension", lodestoneDimension);
         }
 
-        if (lodestonePosition != null) {
+        public Builder lodestoneDimension(@Nullable String lodestoneDimension) {
-            NBTCompound posCompound = new NBTCompound();
+            this.lodestoneDimension = lodestoneDimension;
-            posCompound.setInt("X", (int) lodestonePosition.getX());
+
-            posCompound.setInt("Y", (int) lodestonePosition.getY());
+            if (lodestoneDimension != null) {
-            posCompound.setInt("Z", (int) lodestonePosition.getZ());
+                this.nbt.setString("LodestoneDimension", lodestoneDimension);
-            compound.set("LodestonePos", posCompound);
+            } else {
+                this.nbt.removeTag("LodestoneDimension");
+            }
+
+            return this;
         }
-    }
 
-    @NotNull
+        public Builder lodestonePosition(@Nullable Position lodestonePosition) {
-    @Override
+            this.lodestonePosition = lodestonePosition;
-    public ItemMeta clone() {
-        CompassMeta compassMeta = (CompassMeta) super.clone();
-        compassMeta.lodestoneTracked = lodestoneTracked;
-        compassMeta.lodestoneDimension = lodestoneDimension;
-        compassMeta.lodestonePosition = CloneUtils.optionalClone(lodestonePosition);
 
-        return compassMeta;
+            if (lodestonePosition != null) {
+                NBTCompound posCompound = new NBTCompound();
+                posCompound.setInt("X", (int) lodestonePosition.getX());
+                posCompound.setInt("Y", (int) lodestonePosition.getY());
+                posCompound.setInt("Z", (int) lodestonePosition.getZ());
+                this.nbt.set("LodestonePos", posCompound);
+            } else {
+                this.nbt.removeTag("LodestonePos");
+            }
+
+            return this;
+        }
+
+        @Override
+        public @NotNull CompassMeta build() {
+            return new CompassMeta(this, lodestoneTracked, lodestoneDimension, lodestonePosition);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("LodestoneTracked")) {
+                lodestoneTracked(nbtCompound.getByte("LodestoneTracked") == 1);
+            }
+            if (nbtCompound.containsKey("LodestoneDimension")) {
+                lodestoneDimension(nbtCompound.getString("LodestoneDimension"));
+            }
+            if (nbtCompound.containsKey("LodestonePos")) {
+                final NBTCompound posCompound = nbtCompound.getCompound("LodestonePos");
+                final int x = posCompound.getInt("X");
+                final int y = posCompound.getInt("Y");
+                final int z = posCompound.getInt("Z");
+                lodestonePosition(new Position(x, y, z));
+            }
+        }
+
+        @Override
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
     }
 }

src/main/java/net/minestom/server/item/metadata/CrossbowMeta.java

@@ -1,50 +1,37 @@
 package net.minestom.server.item.metadata;
 
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.item.Material;
 import net.minestom.server.registry.Registries;
 import net.minestom.server.utils.NBTUtils;
-import net.minestom.server.utils.clone.CloneUtils;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
-public class CrossbowMeta extends ItemMeta {
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
 
-    private boolean triple;
+public class CrossbowMeta extends ItemMeta implements ItemMetaBuilder.Provider<SpawnEggMeta.Builder> {
-    private ItemStack projectile1, projectile2, projectile3;
 
-    private boolean charged;
+    private final boolean triple;
-
+    private final ItemStack projectile1, projectile2, projectile3;
-    /**
+    private final boolean charged;
-     * Sets the projectile of this crossbow.
-     *
-     * @param projectile the projectile of the crossbow
-     */
-    public void setProjectile(@NotNull ItemStack projectile) {
-        Check.argCondition(projectile.isAir(), "the projectile of your crossbow isn't visible");
-        this.projectile1 = projectile;
-        this.triple = false;
-    }
-
-    /**
-     * Sets the triple projectiles of this crossbow.
-     *
-     * @param projectile1 the projectile 1
-     * @param projectile2 the projectile 2
-     * @param projectile3 the projectile 3
-     */
-    public void setProjectiles(@NotNull ItemStack projectile1, @NotNull ItemStack projectile2, @NotNull ItemStack projectile3) {
-        Check.argCondition(projectile1.isAir(), "the projectile1 of your crossbow isn't visible");
-        Check.argCondition(projectile2.isAir(), "the projectile2 of your crossbow isn't visible");
-        Check.argCondition(projectile3.isAir(), "the projectile3 of your crossbow isn't visible");
 
+    protected CrossbowMeta(@NotNull ItemMetaBuilder metaBuilder,
+                           boolean triple,
+                           ItemStack projectile1, ItemStack projectile2, ItemStack projectile3,
+                           boolean charged) {
+        super(metaBuilder);
+        this.triple = triple;
         this.projectile1 = projectile1;
         this.projectile2 = projectile2;
         this.projectile3 = projectile3;
-        this.triple = true;
+        this.charged = charged;
     }
 
     /**
@@ -59,27 +46,27 @@ public class CrossbowMeta extends ItemMeta {
     /**
      * Gets the first projectile.
      *
-     * @return the first projectile, null if not present
+     * @return the first projectile
      */
-    public ItemStack getProjectile1() {
+    public @NotNull ItemStack getProjectile1() {
         return projectile1;
     }
 
     /**
      * Gets the second projectile.
      *
-     * @return the second projectile, null if not present
+     * @return the second projectile
      */
-    public ItemStack getProjectile2() {
+    public @NotNull ItemStack getProjectile2() {
         return projectile2;
     }
 
     /**
      * Gets the third projectile.
      *
-     * @return the third projectile, null if not present
+     * @return the third projectile
      */
-    public ItemStack getProjectile3() {
+    public @NotNull ItemStack getProjectile3() {
         return projectile3;
     }
 
@@ -92,115 +79,112 @@ public class CrossbowMeta extends ItemMeta {
         return charged;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Makes the bow charged or uncharged.
-     *
-     * @param charged true to make the crossbow charged, false otherwise
-     */
-    public void setCharged(boolean charged) {
-        this.charged = charged;
-    }
 
-    @Override
+        private boolean triple;
-    public boolean hasNbt() {
+        private ItemStack projectile1, projectile2, projectile3 = ItemStack.AIR;
-        return projectile1 != null && !projectile1.isAir();
+        private boolean charged;
-    }
 
-    @Override
+        /**
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+         * Sets the projectile of this crossbow.
-        if (!(itemMeta instanceof CrossbowMeta))
+         *
-            return false;
+         * @param projectile the projectile of the crossbow, air to remove
+         */
+        public Builder projectile(@NotNull ItemStack projectile) {
+            this.projectile1 = projectile;
+            this.triple = false;
 
-        final CrossbowMeta crossbowMeta = (CrossbowMeta) itemMeta;
+            NBTList<NBTCompound> chargedProjectiles = new NBTList<>(NBTTypes.TAG_Compound);
-        final boolean checkCount = triple && crossbowMeta.triple;
+            if (!projectile.isAir()) {
-        if (!checkCount)
+                chargedProjectiles.add(getItemCompound(projectile));
-            return false;
+            }
+            this.nbt.set("ChargedProjectiles", chargedProjectiles);
 
-        if (projectile1.isSimilar(crossbowMeta.projectile1) &&
+            return this;
-                projectile2.isSimilar(crossbowMeta.projectile2) &&
-                projectile3.isSimilar(crossbowMeta.projectile3)) {
-            return true;
         }
 
-        return !triple && (projectile1.isSimilar(crossbowMeta.projectile1));
+        /**
-    }
+         * Sets the triple projectiles of this crossbow.
+         *
+         * @param projectile1 the projectile 1
+         * @param projectile2 the projectile 2
+         * @param projectile3 the projectile 3
+         */
+        public Builder projectiles(@NotNull ItemStack projectile1, @NotNull ItemStack projectile2, @NotNull ItemStack projectile3) {
+            Check.argCondition(projectile1.isAir(), "the projectile1 of your crossbow isn't visible");
+            Check.argCondition(projectile2.isAir(), "the projectile2 of your crossbow isn't visible");
+            Check.argCondition(projectile3.isAir(), "the projectile3 of your crossbow isn't visible");
 
-    @Override
+            this.projectile1 = projectile1;
-    public void read(@NotNull NBTCompound compound) {
+            this.projectile2 = projectile2;
-        if (compound.containsKey("ChargedProjectiles")) {
+            this.projectile3 = projectile3;
-            final NBTList<NBTCompound> projectilesList = compound.getList("ChargedProjectiles");
+            this.triple = true;
-            int index = 0;
-            for (NBTCompound projectileCompound : projectilesList) {
-                final byte count = projectileCompound.getByte("Count");
-                final String id = projectileCompound.getString("id");
-                final Material material = Registries.getMaterial(id);
 
-                final NBTCompound tagsCompound = projectileCompound.getCompound("tag");
+            NBTList<NBTCompound> chargedProjectiles = new NBTList<>(NBTTypes.TAG_Compound);
+            chargedProjectiles.add(getItemCompound(projectile1));
+            chargedProjectiles.add(getItemCompound(projectile2));
+            chargedProjectiles.add(getItemCompound(projectile3));
+            this.nbt.set("ChargedProjectiles", chargedProjectiles);
 
-                ItemStack itemStack = new ItemStack(material, count);
+            return this;
-                NBTUtils.loadDataIntoItem(itemStack, tagsCompound);
+        }
 
-                index++;
+        /**
+         * Makes the bow charged or uncharged.
+         *
+         * @param charged true to make the crossbow charged, false otherwise
+         */
+        public Builder charged(boolean charged) {
+            this.charged = charged;
+            this.nbt.setByte("Charged", (byte) (charged ? 1 : 0));
+            return this;
+        }
 
-                if (index == 1) {
+        @Override
-                    projectile1 = itemStack;
+        public @NotNull CrossbowMeta build() {
-                } else if (index == 2) {
+            return new CrossbowMeta(this, triple, projectile1, projectile2, projectile3, charged);
-                    projectile2 = itemStack;
+        }
-                } else if (index == 3) {
+
-                    projectile3 = itemStack;
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("ChargedProjectiles")) {
+                final NBTList<NBTCompound> projectilesList = nbtCompound.getList("ChargedProjectiles");
+                List<ItemStack> projectiles = new ArrayList<>();
+                for (NBTCompound projectileCompound : projectilesList) {
+                    final byte count = projectileCompound.getByte("Count");
+                    final String id = projectileCompound.getString("id");
+                    final Material material = Registries.getMaterial(id);
+
+                    final NBTCompound tagsCompound = projectileCompound.getCompound("tag");
+
+                    ItemStack itemStack = NBTUtils.loadItem(material, count, tagsCompound);
+
+                    projectiles.add(itemStack);
+                }
+
+                if (projectiles.size() == 1) {
+                    projectile(projectiles.get(0));
+                } else if (projectiles.size() == 3) {
+                    projectiles(projectiles.get(0), projectiles.get(1), projectiles.get(2));
                 }
 
             }
-        }
 
-        if (compound.containsKey("Charged")) {
+            if (nbtCompound.containsKey("Charged")) {
-            this.charged = compound.getByte("Charged") == 1;
+                charged(nbtCompound.getByte("Charged") == 1);
-        }
-    }
-
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        if (projectile1 != null || projectile2 != null || projectile3 != null) {
-            NBTList<NBTCompound> chargedProjectiles = new NBTList<>(NBTTypes.TAG_Compound);
-            if (projectile1 != null) {
-                chargedProjectiles.add(getItemCompound(projectile1));
             }
-            if (projectile2 != null) {
-                chargedProjectiles.add(getItemCompound(projectile2));
-            }
-            if (projectile3 != null) {
-                chargedProjectiles.add(getItemCompound(projectile3));
-            }
-            compound.set("ChargedProjectiles", chargedProjectiles);
         }
 
-        if (charged) {
+        @Override
-            compound.setByte("Charged", (byte) (charged ? 1 : 0));
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
+
+        private @NotNull NBTCompound getItemCompound(@NotNull ItemStack itemStack) {
+            NBTCompound compound = itemStack.getMeta().toNBT();
+            compound.setByte("Count", (byte) itemStack.getAmount());
+            compound.setString("id", itemStack.getMaterial().getName());
+            return compound;
         }
     }
-
+}
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        CrossbowMeta crossbowMeta = (CrossbowMeta) super.clone();
-        crossbowMeta.triple = triple;
-        crossbowMeta.projectile1 = CloneUtils.optionalClone(projectile1);
-        crossbowMeta.projectile2 = CloneUtils.optionalClone(projectile2);
-        crossbowMeta.projectile3 = CloneUtils.optionalClone(projectile3);
-
-        crossbowMeta.charged = charged;
-
-        return crossbowMeta;
-    }
-
-    @NotNull
-    private NBTCompound getItemCompound(@NotNull ItemStack itemStack) {
-        NBTCompound compound = new NBTCompound();
-
-        compound.setByte("Count", itemStack.getAmount());
-        compound.setString("id", itemStack.getMaterial().getName());
-        NBTUtils.saveDataIntoNBT(itemStack, compound);
-
-        return compound;
-    }
-}

src/main/java/net/minestom/server/item/metadata/EnchantedBookMeta.java

@@ -1,18 +1,25 @@
 package net.minestom.server.item.metadata;
 
-import it.unimi.dsi.fastutil.objects.Object2ShortMap;
-import it.unimi.dsi.fastutil.objects.Object2ShortOpenHashMap;
 import net.minestom.server.item.Enchantment;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.utils.NBTUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
+import java.util.function.Supplier;
 
-public class EnchantedBookMeta extends ItemMeta {
+public class EnchantedBookMeta extends ItemMeta implements ItemMetaBuilder.Provider<EnchantedBookMeta.Builder> {
 
-    private final Object2ShortMap<Enchantment> storedEnchantmentMap = new Object2ShortOpenHashMap<>();
+    private final Map<Enchantment, Short> storedEnchantmentMap;
+
+    protected EnchantedBookMeta(@NotNull ItemMetaBuilder metaBuilder, Map<Enchantment, Short> storedEnchantmentMap) {
+        super(metaBuilder);
+        this.storedEnchantmentMap = new HashMap<>(storedEnchantmentMap);
+    }
 
     /**
      * Gets the stored enchantment map.
@@ -20,76 +27,41 @@ public class EnchantedBookMeta extends ItemMeta {
      *
      * @return an unmodifiable map containing the item stored enchantments
      */
-    @NotNull
+    public @NotNull Map<Enchantment, Short> getStoredEnchantmentMap() {
-    public Map<Enchantment, Short> getStoredEnchantmentMap() {
         return Collections.unmodifiableMap(storedEnchantmentMap);
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Sets a stored enchantment level.
+
-     *
+        private Map<Enchantment, Short> enchantments = new HashMap<>();
-     * @param enchantment the enchantment type
+
-     * @param level       the enchantment level
+        public @NotNull Builder enchantments(Map<Enchantment, Short> enchantments) {
-     */
+            this.enchantments = enchantments;
-    public void setStoredEnchantment(@NotNull Enchantment enchantment, short level) {
+            NBTUtils.writeEnchant(nbt, "StoredEnchantments", enchantments);
-        if (level < 1) {
+            return this;
-            removeStoredEnchantment(enchantment);
-            return;
         }
 
-        this.storedEnchantmentMap.put(enchantment, level);
+        public @NotNull Builder enchantment(Enchantment enchantment, short level) {
-    }
+            this.enchantments.put(enchantment, level);
-
+            enchantments(enchantments);
-    /**
+            return this;
-     * Removes a stored enchantment.
-     *
-     * @param enchantment the enchantment type
-     */
-    public void removeStoredEnchantment(@NotNull Enchantment enchantment) {
-        this.storedEnchantmentMap.removeShort(enchantment);
-    }
-
-    /**
-     * Gets a stored enchantment level.
-     *
-     * @param enchantment the enchantment type
-     * @return the stored enchantment level, 0 if not present
-     */
-    public int getStoredEnchantmentLevel(@NotNull Enchantment enchantment) {
-        return this.storedEnchantmentMap.getOrDefault(enchantment, (short) 0);
-    }
-
-    @Override
-    public boolean hasNbt() {
-        return !storedEnchantmentMap.isEmpty();
-    }
-
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        return itemMeta instanceof EnchantedBookMeta &&
-                ((EnchantedBookMeta) itemMeta).storedEnchantmentMap.equals(storedEnchantmentMap);
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("StoredEnchantments")) {
-            NBTUtils.loadEnchantments(compound.getList("StoredEnchantments"), this::setStoredEnchantment);
         }
-    }
 
-    @Override
+        @Override
-    public void write(@NotNull NBTCompound compound) {
+        public @NotNull EnchantedBookMeta build() {
-        if (!storedEnchantmentMap.isEmpty()) {
+            return new EnchantedBookMeta(this, enchantments);
-            NBTUtils.writeEnchant(compound, "StoredEnchantments", storedEnchantmentMap);
         }
-    }
 
-    @NotNull
+        @Override
-    @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
-    public ItemMeta clone() {
+            if (nbtCompound.containsKey("StoredEnchantments")) {
-        EnchantedBookMeta enchantedBookMeta = (EnchantedBookMeta) super.clone();
+                NBTUtils.loadEnchantments(nbtCompound.getList("StoredEnchantments"), this::enchantment);
-        enchantedBookMeta.storedEnchantmentMap.putAll(storedEnchantmentMap);
+            }
+        }
 
-        return enchantedBookMeta;
+        @Override
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
     }
 }

src/main/java/net/minestom/server/item/metadata/FireworkEffectMeta.java

@@ -1,92 +1,52 @@
 package net.minestom.server.item.metadata;
 
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.item.firework.FireworkEffect;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
-public class FireworkEffectMeta extends ItemMeta {
+import java.util.function.Supplier;
 
-    private FireworkEffect fireworkEffect;
+public class FireworkEffectMeta extends ItemMeta implements ItemMetaBuilder.Provider<FireworkEffectMeta.Builder> {
+
+    private final FireworkEffect fireworkEffect;
+
+    protected FireworkEffectMeta(@NotNull ItemMetaBuilder metaBuilder, FireworkEffect fireworkEffect) {
+        super(metaBuilder);
+        this.fireworkEffect = fireworkEffect;
+    }
 
-    /**
-     * Retrieves the firework effect for this meta.
-     *
-     * @return The current firework effect, or {@code null} if none.
-     */
-    @Nullable
     public FireworkEffect getFireworkEffect() {
         return fireworkEffect;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Changes the {@link FireworkEffect} for this item meta.
-     *
-     * @param fireworkEffect The new firework effect, or {@code null}.
-     */
-    public void setFireworkEffect(@Nullable FireworkEffect fireworkEffect) {
-        this.fireworkEffect = fireworkEffect;
-    }
 
-    /**
+        private FireworkEffect fireworkEffect;
-     * Whether if this item meta has an effect.
-     *
-     * @return {@code true} if this item meta has an effect, otherwise {@code false}.
-     */
-    public boolean hasFireworkEffect() {
-        return this.fireworkEffect != null;
-    }
 
-    /**
+        public Builder effect(@Nullable FireworkEffect fireworkEffect) {
-     * {@inheritDoc}
+            this.fireworkEffect = fireworkEffect;
-     */
+            this.nbt.set("Explosion", this.fireworkEffect.asCompound());
-    @Override
+            return this;
-    public boolean hasNbt() {
-        return this.hasFireworkEffect();
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        if (!(itemMeta instanceof FireworkEffectMeta)) {
-            return false;
         }
 
-        FireworkEffectMeta fireworkEffectMeta = (FireworkEffectMeta) itemMeta;
+        @Override
-        return fireworkEffectMeta.fireworkEffect == this.fireworkEffect;
+        public @NotNull FireworkEffectMeta build() {
-    }
+            return new FireworkEffectMeta(this, fireworkEffect);
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("Explosion")) {
-            this.fireworkEffect = FireworkEffect.fromCompound(compound.getCompound("Explosion"));
         }
 
-    }
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("Explosion")) {
+                effect(FireworkEffect.fromCompound(nbtCompound.getCompound("Explosion")));
+            }
+        }
 
-    /**
+        @Override
-     * {@inheritDoc}
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-     */
+            return Builder::new;
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        if (this.fireworkEffect != null) {
-            compound.set("Explosion", this.fireworkEffect.asCompound());
         }
     }
-
+}
-    /**
-     * {@inheritDoc}
-     */
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        FireworkEffectMeta fireworkEffectMeta = (FireworkEffectMeta) super.clone();
-        fireworkEffectMeta.fireworkEffect = this.fireworkEffect;
-        return fireworkEffectMeta;
-    }
-}

src/main/java/net/minestom/server/item/metadata/FireworkMeta.java

@@ -1,179 +1,92 @@
 package net.minestom.server.item.metadata;
 
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.item.firework.FireworkEffect;
 import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
-import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Supplier;
 
-/**
+public class FireworkMeta extends ItemMeta implements ItemMetaBuilder.Provider<FireworkMeta.Builder> {
- * Represents a firework rocket meta data and its effects.
- */
-public class FireworkMeta extends ItemMeta {
 
-    private List<FireworkEffect> effects = new CopyOnWriteArrayList<>();
+    private final List<FireworkEffect> effects;
-    private byte flightDuration;
+    private final byte flightDuration;
 
-    /**
+    protected FireworkMeta(@NotNull ItemMetaBuilder metaBuilder, List<FireworkEffect> effects,
-     * Adds a firework effect to this firework.
+                           byte flightDuration) {
-     *
+        super(metaBuilder);
-     * @param effect The firework effect to be added.
+        this.effects = new ArrayList<>(effects);
-     */
-    public void addFireworkEffect(FireworkEffect effect) {
-        this.effects.add(effect);
-    }
-
-    /**
-     * Adds an array of firework effects to this firework.
-     *
-     * @param effects An array of firework effects to be added.
-     */
-    public void addFireworkEffects(FireworkEffect... effects) {
-        this.effects.addAll(Arrays.asList(effects));
-    }
-
-    /**
-     * Removes a firework effect from this firework.
-     *
-     * @param index The index of the firework effect to be removed.
-     * @throws IndexOutOfBoundsException If index {@literal < 0 or index >} {@link #getEffectSize()}
-     */
-    public void removeFireworkEffect(int index) throws IndexOutOfBoundsException {
-        this.effects.remove(index);
-    }
-
-    /**
-     * Removes a firework effects from this firework.
-     *
-     * @param effect The effect to be removed.
-     */
-    public void removeFireworkEffect(FireworkEffect effect) {
-        this.effects.remove(effect);
-    }
-
-    /**
-     * Retrieves a collection with all effects in this firework.
-     *
-     * @return A collection with all effects in this firework.
-     */
-    public List<FireworkEffect> getEffects() {
-        return effects;
-    }
-
-    /**
-     * Retrieves the size of effects in this firework.
-     *
-     * @return The size of the effects.
-     */
-    public int getEffectSize() {
-        return this.effects.size();
-    }
-
-    /**
-     * Removes all effects from this firework.
-     */
-    public void clearEffects() {
-        this.effects.clear();
-    }
-
-    /**
-     * Whether this firework has any effects.
-     *
-     * @return {@code true} if this firework has any effects, otherwise {@code false}.
-     */
-    public boolean hasEffects() {
-        return this.effects.isEmpty();
-    }
-
-    /**
-     * Changes the flight duration of this firework.
-     *
-     * @param flightDuration The new flight duration for this firework.
-     */
-    public void setFlightDuration(byte flightDuration) {
         this.flightDuration = flightDuration;
     }
 
-    /**
+    public List<FireworkEffect> getEffects() {
-     * Returns the flight duration of this firework
+        return Collections.unmodifiableList(effects);
-     * @return the flight duration of this firework
+    }
-     */
+
     public byte getFlightDuration() {
         return flightDuration;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * {@inheritDoc}
-     */
-    @Override
-    public boolean hasNbt() {
-        return this.flightDuration == 0 || !this.effects.isEmpty();
-    }
 
-    /**
+        private List<FireworkEffect> effects = new CopyOnWriteArrayList<>();
-     * {@inheritDoc}
+        private byte flightDuration;
-     */
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        return false;
-    }
 
-    /**
+        public Builder effects(List<FireworkEffect> effects) {
-     * {@inheritDoc}
+            this.effects = effects;
-     */
+            handleCompound("Fireworks", nbtCompound -> {
-    @Override
+                NBTList<NBTCompound> explosions = new NBTList<>(NBTTypes.TAG_Compound);
-    public void read(@NotNull NBTCompound compound) {
+                for (FireworkEffect effect : this.effects) {
-        this.effects.clear();
+                    explosions.add(effect.asCompound());
-        if (compound.containsKey("Fireworks")) {
+                }
-            NBTCompound fireworksCompound = compound.getCompound("Fireworks");
+                nbtCompound.set("Explosions", explosions);
+            });
+            return this;
+        }
 
-            if (fireworksCompound.containsKey("Flight")) {
+        public Builder flightDuration(byte flightDuration) {
-                this.flightDuration = fireworksCompound.getAsByte("Flight");
+            this.flightDuration = flightDuration;
-            }
+            handleCompound("Fireworks", nbtCompound -> {
+                nbtCompound.setByte("Flight", this.flightDuration);
+            });
+            return this;
+        }
 
-            if (fireworksCompound.containsKey("Explosions")) {
+        @Override
-                NBTList<NBTCompound> explosions = fireworksCompound.getList("Explosions");
+        public @NotNull FireworkMeta build() {
+            return new FireworkMeta(this, effects, flightDuration);
+        }
 
-                for (NBTCompound explosion : explosions) {
+        @Override
-                    this.effects.add(FireworkEffect.fromCompound(explosion));
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("Fireworks")) {
+                NBTCompound fireworksCompound = nbtCompound.getCompound("Fireworks");
+
+                if (fireworksCompound.containsKey("Flight")) {
+                    flightDuration(fireworksCompound.getAsByte("Flight"));
+                }
+
+                if (fireworksCompound.containsKey("Explosions")) {
+                    NBTList<NBTCompound> explosions = fireworksCompound.getList("Explosions");
+
+                    for (NBTCompound explosion : explosions) {
+                        this.effects.add(FireworkEffect.fromCompound(explosion));
+                    }
+                    effects(effects);
                 }
             }
-
-        }
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        NBTCompound fireworksCompound = new NBTCompound();
-        fireworksCompound.setByte("Flight", this.flightDuration);
-
-        NBTList<NBTCompound> explosions = new NBTList<>(NBTTypes.TAG_Compound);
-        for (FireworkEffect effect : this.effects) {
-            explosions.add(effect.asCompound());
         }
 
-        fireworksCompound.set("Explosions", explosions);
+        @Override
-
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-        compound.set("Fireworks", fireworksCompound);
+            return Builder::new;
+        }
     }
-
+}
-    /**
-     * {@inheritDoc}
-     */
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        FireworkMeta fireworkMeta = (FireworkMeta) super.clone();
-        fireworkMeta.effects = this.effects;
-        fireworkMeta.flightDuration = this.flightDuration;
-
-        return fireworkMeta;
-    }
-}

src/main/java/net/minestom/server/item/metadata/ItemMeta.java

@@ -1,61 +0,0 @@
-package net.minestom.server.item.metadata;
-
-import net.minestom.server.MinecraftServer;
-import net.minestom.server.item.ItemStack;
-import net.minestom.server.utils.clone.PublicCloneable;
-import org.jetbrains.annotations.NotNull;
-import org.jglrxavpok.hephaistos.nbt.NBTCompound;
-
-/**
- * Represents nbt data only available for a type of item.
- */
-public abstract class ItemMeta implements PublicCloneable<ItemMeta> {
-
-    /**
-     * Gets if this meta object contains any useful data to send to the client.
-     *
-     * @return true if this item has nbt data, false otherwise
-     */
-    public abstract boolean hasNbt();
-
-    /**
-     * Gets if the two ItemMeta are similar.
-     * <p>
-     * It is used by {@link ItemStack#isSimilar(ItemStack)}.
-     *
-     * @param itemMeta the second item meta to check
-     * @return true if the two meta are similar, false otherwise
-     */
-    public abstract boolean isSimilar(@NotNull ItemMeta itemMeta);
-
-    /**
-     * Reads nbt data from a compound.
-     * <p>
-     * WARNING: it is possible that it contains no useful data,
-     * it has to be checked before getting anything.
-     *
-     * @param compound the compound containing the data
-     */
-    public abstract void read(@NotNull NBTCompound compound);
-
-    /**
-     * Writes nbt data to a compound.
-     *
-     * @param compound the compound receiving the item meta data
-     */
-    public abstract void write(@NotNull NBTCompound compound);
-
-    /**
-     * {@inheritDoc}
-     */
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        try {
-            return (ItemMeta) super.clone();
-        } catch (CloneNotSupportedException e) {
-            MinecraftServer.getExceptionManager().handleException(e);
-            throw new IllegalStateException("Weird thing happened");
-        }
-    }
-}

src/main/java/net/minestom/server/item/metadata/LeatherArmorMeta.java

@@ -1,175 +1,61 @@
 package net.minestom.server.item.metadata;
 
-import net.minestom.server.chat.ChatColor;
 import net.minestom.server.color.Color;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
-/**
+import java.util.function.Supplier;
- * Represents the item meta for leather armor parts.
- */
-public class LeatherArmorMeta extends ItemMeta {
-    private boolean modified;
-    private Color color;
 
-    /**
+public class LeatherArmorMeta extends ItemMeta implements ItemMetaBuilder.Provider<LeatherArmorMeta.Builder> {
-     * Sets the color of the leather armor piece.
-     *
-     * @param color the color of the leather armor
-     * @deprecated Use {@link #setColor(Color)}
-     */
-    @Deprecated
-    public void setColor(ChatColor color) {
-        this.setColor(color.asColor());
-    }
 
-    /**
+    private final Color color;
-     * Changes the color of the leather armor piece.
-     *
-     * @param red   The red color of the leather armor piece.
-     * @param green The green color of the leather armor piece.
-     * @param blue  The blue color of the leather armor piece.
-     * @deprecated Use {@link #setColor(Color)}
-     */
-    @Deprecated
-    public void setColor(byte red, byte green, byte blue) {
-        this.setColor(new Color(red, green, blue));
-    }
 
-    /**
+    protected LeatherArmorMeta(@NotNull ItemMetaBuilder metaBuilder, @Nullable Color color) {
-     * Sets the color of this leather armor piece.
+        super(metaBuilder);
-     *
-     * @param color the new color
-     */
-    public void setColor(@NotNull Color color) {
-        this.modified = !color.equals(this.color);
         this.color = color;
     }
 
-    /**
+    public @Nullable Color getColor() {
-     * Gets the color of this leather armor piece.
+        return color;
-     *
-     * @return the color
-     */
-    public @NotNull Color getColor() {
-        return this.color;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Resets the color to the default leather one.
-     */
-    public void reset() {
-        this.color = new Color(0, 0, 0);
-        this.modified = false;
-    }
 
-    /**
+        private Color color;
-     * Gets the red component.
-     *
-     * @return the red component
-     * @deprecated Use {@link #getColor}
-     */
-    @Deprecated
-    public int getRed() {
-        return this.color.getRed();
-    }
 
-    /**
+        public Builder color(@Nullable Color color) {
-     * Gets the green component.
+            this.color = color;
-     *
+            handleCompound("display", nbtCompound -> {
-     * @return the green component
+                if (color != null) {
-     * @deprecated Use {@link #getColor}
+                    nbtCompound.setInt("color", color.asRGB());
-     */
+                } else {
-    @Deprecated
+                    nbtCompound.removeTag("color");
-    public int getGreen() {
+                }
-        return this.color.getGreen();
+            });
-    }
+            return this;
+        }
 
-    /**
+        @Override
-     * Gets the blue component.
+        public @NotNull LeatherArmorMeta build() {
-     *
+            return new LeatherArmorMeta(this, color);
-     * @return the blue component
+        }
-     * @deprecated Use {@link #getColor}
-     */
-    @Deprecated
-    public int getBlue() {
-        return this.color.getBlue();
-    }
 
-    /**
+        @Override
-     * Gets if the color of this armor piece have been changed.
+        public void read(@NotNull NBTCompound nbtCompound) {
-     *
+            if (nbtCompound.containsKey("display")) {
-     * @return true if the color has been changed, false otherwise
+                final NBTCompound displayCompound = nbtCompound.getCompound("display");
-     */
+                if (displayCompound.containsKey("color")) {
-    public boolean isModified() {
+                    color(new Color(displayCompound.getInt("color")));
-        return modified;
+                }
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public boolean hasNbt() {
-        return modified;
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        if (!(itemMeta instanceof LeatherArmorMeta)) return false;
-        final LeatherArmorMeta leatherArmorMeta = (LeatherArmorMeta) itemMeta;
-        return leatherArmorMeta.isModified() == isModified()
-                && leatherArmorMeta.getColor().equals(getColor());
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("display")) {
-            final NBTCompound nbtCompound = compound.getCompound("display");
-            if (nbtCompound.containsKey("color")) {
-                final int color = nbtCompound.getInt("color");
-
-                // Sets the color of the leather armor piece
-                // This also fixes that the armor pieces do not decolorize again when you are in creative
-                // mode.
-                this.setColor(new Color(color));
             }
         }
-    }
 
-    /**
+        @Override
-     * {@inheritDoc}
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-     */
+            return Builder::new;
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        if (modified) {
-            NBTCompound displayCompound;
-            if (!compound.containsKey("display")) {
-                displayCompound = new NBTCompound();
-            } else {
-                displayCompound = compound.getCompound("display");
-            }
-            displayCompound.setInt("color", color.asRGB());
-            // Adds the color compound to the display compound
-            compound.set("display", displayCompound);
         }
     }
-
-    /**
-     * {@inheritDoc}
-     */
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        LeatherArmorMeta leatherArmorMeta = (LeatherArmorMeta) super.clone();
-        leatherArmorMeta.modified = this.isModified();
-        leatherArmorMeta.color = color;
-
-        return leatherArmorMeta;
-    }
 }

src/main/java/net/minestom/server/item/metadata/MapMeta.java

@@ -3,28 +3,36 @@ package net.minestom.server.item.metadata;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.chat.ChatColor;
 import net.minestom.server.color.Color;
-import net.minestom.server.utils.clone.CloneUtils;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.utils.clone.PublicCloneable;
 import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Supplier;
 
 public class MapMeta extends ItemMeta {
 
-    private int mapId;
+    private final int mapId;
-    private int mapScaleDirection = 1;
+    private final int mapScaleDirection;
-    private List<MapDecoration> decorations = new CopyOnWriteArrayList<>();
+    private final List<MapDecoration> decorations;
-    private Color mapColor = new Color(0, 0, 0);
+    private final Color mapColor;
 
-    public MapMeta() {
+    protected MapMeta(ItemMetaBuilder metaBuilder,
-    }
+                      int mapId,
-
+                      int mapScaleDirection,
-    public MapMeta(int id) {
+                      @NotNull List<MapDecoration> decorations,
-        this.mapId = id;
+                      @NotNull Color mapColor) {
+        super(metaBuilder);
+        this.mapId = mapId;
+        this.mapScaleDirection = mapScaleDirection;
+        this.decorations = decorations;
+        this.mapColor = mapColor;
     }
 
     /**
@@ -36,15 +44,6 @@ public class MapMeta extends ItemMeta {
         return mapId;
     }
 
-    /**
-     * Changes the map id.
-     *
-     * @param mapId the new map id
-     */
-    public void setMapId(int mapId) {
-        this.mapId = mapId;
-    }
-
     /**
      * Gets the map scale direction.
      *
@@ -54,15 +53,6 @@ public class MapMeta extends ItemMeta {
         return mapScaleDirection;
     }
 
-    /**
-     * Changes the map scale direction.
-     *
-     * @param mapScaleDirection the new map scale direction
-     */
-    public void setMapScaleDirection(int mapScaleDirection) {
-        this.mapScaleDirection = mapScaleDirection;
-    }
-
     /**
      * Gets the map decorations.
      *
@@ -72,15 +62,6 @@ public class MapMeta extends ItemMeta {
         return decorations;
     }
 
-    /**
-     * Changes the map decorations list.
-     *
-     * @param decorations the new map decorations list
-     */
-    public void setDecorations(List<MapDecoration> decorations) {
-        this.decorations = decorations;
-    }
-
     /**
      * Gets the map color.
      *
@@ -101,94 +82,28 @@ public class MapMeta extends ItemMeta {
         return this.mapColor;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Changes the map color.
-     *
-     * @param mapColor the new map color
-     * @deprecated Use {@link #setMapColor(Color)}
-     */
-    @Deprecated
-    public void setMapColor(ChatColor mapColor) {
-        this.setMapColor(mapColor.asColor());
-    }
 
-    /**
+        private int mapId;
-     * Changes the map color.
+        private int mapScaleDirection = 1;
-     *
+        private List<MapDecoration> decorations = new CopyOnWriteArrayList<>();
-     * @param color the new map color
+        private Color mapColor = new Color(0, 0, 0);
-     */
-    public void setMapColor(@NotNull Color color) {
-        this.mapColor = color;
-    }
 
-    @Override
+        public Builder mapId(int value) {
-    public boolean hasNbt() {
+            this.mapId = value;
-        return true;
+            this.nbt.setInt("map", mapId);
-    }
+            return this;
-
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        if (!(itemMeta instanceof MapMeta))
-            return false;
-
-        final MapMeta mapMeta = (MapMeta) itemMeta;
-        return mapMeta.mapId == mapId &&
-                mapMeta.mapScaleDirection == mapScaleDirection &&
-                mapMeta.decorations.equals(decorations) &&
-                mapMeta.mapColor == mapColor;
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("map")) {
-            this.mapId = compound.getAsInt("map");
         }
 
-        if (compound.containsKey("map_scale_direction")) {
+        public Builder mapScaleDirection(int value) {
-            this.mapScaleDirection = compound.getAsInt("map_scale_direction");
+            this.mapScaleDirection = value;
+            this.nbt.setInt("map_scale_direction", value);
+            return this;
         }
 
-        if (compound.containsKey("Decorations")) {
+        public Builder decorations(List<MapDecoration> value) {
-            final NBTList<NBTCompound> decorationsList = compound.getList("Decorations");
+            this.decorations = value;
-            for (NBTCompound decorationCompound : decorationsList) {
-                final String id = decorationCompound.getString("id");
-                final byte type = decorationCompound.getAsByte("type");
-                byte x = 0;
 
-                if (decorationCompound.containsKey("x")) {
-                    x = decorationCompound.getAsByte("x");
-                }
-
-                byte z = 0;
-                if (decorationCompound.containsKey("z")) {
-                    z = decorationCompound.getAsByte("z");
-                }
-
-                double rotation = 0.0;
-                if (decorationCompound.containsKey("rot")) {
-                    rotation = decorationCompound.getAsDouble("rot");
-                }
-
-                this.decorations.add(new MapDecoration(id, type, x, z, rotation));
-            }
-        }
-
-        if (compound.containsKey("display")) {
-            final NBTCompound displayCompound = compound.getCompound("display");
-            if (displayCompound.containsKey("MapColor")) {
-                this.mapColor = new Color(displayCompound.getAsInt("MapColor"));
-            }
-        }
-
-    }
-
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        compound.setInt("map", mapId);
-
-        compound.setInt("map_scale_direction", mapScaleDirection);
-
-        if (!decorations.isEmpty()) {
             NBTList<NBTCompound> decorationsList = new NBTList<>(NBTTypes.TAG_Compound);
             for (MapDecoration decoration : decorations) {
                 NBTCompound decorationCompound = new NBTCompound();
@@ -200,29 +115,80 @@ public class MapMeta extends ItemMeta {
 
                 decorationsList.add(decorationCompound);
             }
-            compound.set("Decorations", decorationsList);
+            this.nbt.set("Decorations", decorationsList);
+
+            return this;
         }
 
-        {
+        public Builder mapColor(Color value) {
+            this.mapColor = value;
+
             NBTCompound displayCompound;
-            if (compound.containsKey("display")) {
+            if (nbt.containsKey("display")) {
-                displayCompound = compound.getCompound("display");
+                displayCompound = nbt.getCompound("display");
             } else {
                 displayCompound = new NBTCompound();
+                this.nbt.set("display", displayCompound);
             }
             displayCompound.setInt("MapColor", mapColor.asRGB());
-        }
-    }
 
-    @NotNull
+            return this;
-    @Override
+        }
-    public ItemMeta clone() {
+
-        MapMeta mapMeta = (MapMeta) super.clone();
+        @Override
-        mapMeta.setMapId(mapId);
+        public @NotNull ItemMeta build() {
-        mapMeta.setMapScaleDirection(mapScaleDirection);
+            return new MapMeta(this, mapId, mapScaleDirection, decorations, mapColor);
-        mapMeta.decorations = CloneUtils.cloneCopyOnWriteArrayList(decorations);
+        }
-        mapMeta.setMapColor(mapColor);
+
-        return mapMeta;
+        @Override
+        public void read(@NotNull NBTCompound compound) {
+            if (compound.containsKey("map")) {
+                mapId(compound.getAsInt("map"));
+            }
+
+            if (compound.containsKey("map_scale_direction")) {
+                mapScaleDirection(compound.getAsInt("map_scale_direction"));
+            }
+
+            if (compound.containsKey("Decorations")) {
+                final NBTList<NBTCompound> decorationsList = compound.getList("Decorations");
+                List<MapDecoration> mapDecorations = new ArrayList<>();
+                for (NBTCompound decorationCompound : decorationsList) {
+                    final String id = decorationCompound.getString("id");
+                    final byte type = decorationCompound.getAsByte("type");
+                    byte x = 0;
+
+                    if (decorationCompound.containsKey("x")) {
+                        x = decorationCompound.getAsByte("x");
+                    }
+
+                    byte z = 0;
+                    if (decorationCompound.containsKey("z")) {
+                        z = decorationCompound.getAsByte("z");
+                    }
+
+                    double rotation = 0.0;
+                    if (decorationCompound.containsKey("rot")) {
+                        rotation = decorationCompound.getAsDouble("rot");
+                    }
+
+                    mapDecorations.add(new MapDecoration(id, type, x, z, rotation));
+                }
+                decorations(mapDecorations);
+            }
+
+            if (compound.containsKey("display")) {
+                final NBTCompound displayCompound = compound.getCompound("display");
+                if (displayCompound.containsKey("MapColor")) {
+                    mapColor(new Color(displayCompound.getAsInt("MapColor")));
+                }
+            }
+        }
+
+        @Override
+        protected @NotNull Supplier<@NotNull ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
     }
 
     public static class MapDecoration implements PublicCloneable<MapDecoration> {

src/main/java/net/minestom/server/item/metadata/PlayerHeadMeta.java

@@ -1,7 +1,8 @@
 package net.minestom.server.item.metadata;
 
-import net.minestom.server.entity.Player;
 import net.minestom.server.entity.PlayerSkin;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.utils.Utils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -10,152 +11,85 @@ import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
 import java.util.UUID;
+import java.util.function.Supplier;
 
-/**
+public class PlayerHeadMeta extends ItemMeta implements ItemMetaBuilder.Provider<PlayerHeadMeta.Builder> {
- * Represents a skull that can have an owner.
- */
-public class PlayerHeadMeta extends ItemMeta {
 
-    private UUID skullOwner;
+    private final UUID skullOwner;
-    private PlayerSkin playerSkin;
+    private final PlayerSkin playerSkin;
 
-    /**
+    protected PlayerHeadMeta(@NotNull ItemMetaBuilder metaBuilder, UUID skullOwner,
-     * Sets the owner of the skull.
+                             PlayerSkin playerSkin) {
-     *
+        super(metaBuilder);
-     * @param player The new owner of the skull.
+        this.skullOwner = skullOwner;
-     * @return {@code true} if the owner was successfully set, otherwise {@code false}.
+        this.playerSkin = playerSkin;
-     */
-    public boolean setOwningPlayer(@NotNull Player player) {
-        if (player.getSkin() != null) {
-            this.skullOwner = player.getUuid();
-            this.playerSkin = player.getSkin();
-            return true;
-        }
-        return false;
     }
 
-    /**
-     * Retrieves the owner of the head.
-     *
-     * @return The head's owner.
-     */
-    @Nullable
     public UUID getSkullOwner() {
         return skullOwner;
     }
 
-    /**
-     * Changes the owner of the head.
-     *
-     * @param skullOwner The new head owner.
-     */
-    public void setSkullOwner(@NotNull UUID skullOwner) {
-        this.skullOwner = skullOwner;
-    }
-
-    /**
-     * Retrieves the skin of the head.
-     *
-     * @return The head's skin.
-     */
-    @Nullable
     public PlayerSkin getPlayerSkin() {
         return playerSkin;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Changes the skin of the head.
-     *
-     * @param playerSkin The new skin for the head.
-     */
-    public void setPlayerSkin(@NotNull PlayerSkin playerSkin) {
-        this.playerSkin = playerSkin;
-    }
 
-    /**
+        private UUID skullOwner;
-     * {@inheritDoc}
+        private PlayerSkin playerSkin;
-     */
-    @Override
-    public boolean hasNbt() {
-        return this.skullOwner != null || playerSkin != null;
-    }
 
-    /**
+        public Builder skullOwner(@Nullable UUID skullOwner) {
-     * {@inheritDoc}
+            this.skullOwner = skullOwner;
-     */
+            handleCompound("SkullOwner", nbtCompound -> {
-    @Override
+                nbtCompound.setIntArray("Id", Utils.uuidToIntArray(this.skullOwner));
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+            });
-        if (!(itemMeta instanceof PlayerHeadMeta))
+            return this;
-            return false;
+        }
-        final PlayerHeadMeta playerHeadMeta = (PlayerHeadMeta) itemMeta;
-        return playerHeadMeta.playerSkin == playerSkin;
-    }
 
-    /**
+        public Builder playerSkin(@Nullable PlayerSkin playerSkin) {
-     * {@inheritDoc}
+            this.playerSkin = playerSkin;
-     */
+            handleCompound("SkullOwner", nbtCompound -> {
-    @Override
+                NBTList<NBTCompound> textures = new NBTList<>(NBTTypes.TAG_Compound);
-    public void read(@NotNull NBTCompound compound) {
+                String value = this.playerSkin.getTextures() == null ? "" : this.playerSkin.getTextures();
-        if (compound.containsKey("SkullOwner")) {
+                String signature = this.playerSkin.getSignature() == null ? "" : this.playerSkin.getSignature();
-            NBTCompound skullOwnerCompound = compound.getCompound("SkullOwner");
+                textures.add(new NBTCompound().setString("Value", value).setString("Signature", signature));
+                nbtCompound.set("Properties", new NBTCompound().set("textures", textures));
+            });
+            return this;
+        }
 
-            if (skullOwnerCompound.containsKey("Id")) {
+        @Override
-                this.skullOwner = Utils.intArrayToUuid(skullOwnerCompound.getIntArray("Id"));
+        public @NotNull PlayerHeadMeta build() {
-            }
+            return new PlayerHeadMeta(this, skullOwner, playerSkin);
+        }
 
-            if (skullOwnerCompound.containsKey("Properties")) {
+        @Override
-                NBTCompound propertyCompound = skullOwnerCompound.getCompound("Properties");
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("SkullOwner")) {
+                NBTCompound skullOwnerCompound = nbtCompound.getCompound("SkullOwner");
 
-                if (propertyCompound.containsKey("textures")) {
+                if (skullOwnerCompound.containsKey("Id")) {
-                    NBTList<NBTCompound> textures = propertyCompound.getList("textures");
+                    skullOwner(Utils.intArrayToUuid(skullOwnerCompound.getIntArray("Id")));
-                    if (textures != null) {
-                        NBTCompound nbt = textures.get(0);
-                        this.playerSkin = new PlayerSkin(nbt.getString("Value"), nbt.getString("Signature"));
-                    }
                 }
 
+                if (skullOwnerCompound.containsKey("Properties")) {
+                    NBTCompound propertyCompound = skullOwnerCompound.getCompound("Properties");
+
+                    if (propertyCompound.containsKey("textures")) {
+                        NBTList<NBTCompound> textures = propertyCompound.getList("textures");
+                        if (textures != null) {
+                            NBTCompound nbt = textures.get(0);
+                            playerSkin(new PlayerSkin(nbt.getString("Value"), nbt.getString("Signature")));
+                        }
+                    }
+
+                }
             }
-
-        }
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        NBTCompound skullOwnerCompound = new NBTCompound();
-        // Sets the identifier for the skull
-        if (this.skullOwner != null)
-            skullOwnerCompound.setIntArray("Id", Utils.uuidToIntArray(this.skullOwner));
-
-        if (this.playerSkin == null && this.skullOwner != null) {
-            this.playerSkin = PlayerSkin.fromUuid(this.skullOwner.toString());
         }
 
-        if (this.playerSkin != null) {
+        @Override
-            NBTList<NBTCompound> textures = new NBTList<>(NBTTypes.TAG_Compound);
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-            String value = this.playerSkin.getTextures() == null ? "" : this.playerSkin.getTextures();
+            return Builder::new;
-            String signature = this.playerSkin.getSignature() == null ? "" : this.playerSkin.getSignature();
-            textures.add(new NBTCompound().setString("Value", value).setString("Signature", signature));
-            skullOwnerCompound.set("Properties", new NBTCompound().set("textures", textures));
         }
-
-        compound.set("SkullOwner", skullOwnerCompound);
-
     }
-
-    /**
-     * {@inheritDoc}
-     */
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        PlayerHeadMeta playerHeadMeta = (PlayerHeadMeta) super.clone();
-        playerHeadMeta.skullOwner = this.skullOwner;
-        playerHeadMeta.playerSkin = this.playerSkin;
-        return playerHeadMeta;
-    }
-
-
 }

src/main/java/net/minestom/server/item/metadata/PotionMeta.java

@@ -1,11 +1,11 @@
 package net.minestom.server.item.metadata;
 
-import net.minestom.server.chat.ChatColor;
 import net.minestom.server.color.Color;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.potion.CustomPotionEffect;
 import net.minestom.server.potion.PotionType;
 import net.minestom.server.registry.Registries;
-import net.minestom.server.utils.clone.CloneUtils;
 import net.minestom.server.utils.time.TimeUnit;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -13,124 +13,53 @@ import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
+import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Supplier;
 
-/**
+public class PotionMeta extends ItemMeta implements ItemMetaBuilder.Provider<PotionMeta.Builder> {
- * Item meta for
- * {@link net.minestom.server.item.Material#POTION},
- * {@link net.minestom.server.item.Material#LINGERING_POTION},
- * {@link net.minestom.server.item.Material#SPLASH_POTION},
- * {@link net.minestom.server.item.Material#TIPPED_ARROW}.
- */
-public class PotionMeta extends ItemMeta {
 
-    private PotionType potionType;
+    private final PotionType potionType;
+    private final List<CustomPotionEffect> customPotionEffects;
+    private final Color color;
 
-    // Not final because of #clone()
+    protected PotionMeta(@NotNull ItemMetaBuilder metaBuilder, @Nullable PotionType potionType,
-    private List<CustomPotionEffect> customPotionEffects = new CopyOnWriteArrayList<>();
+                         List<CustomPotionEffect> customPotionEffects,
+                         Color color) {
+        super(metaBuilder);
+        this.potionType = potionType;
+        this.customPotionEffects = new ArrayList<>(customPotionEffects);
+        this.color = color;
+    }
 
-    private Color color;
-
-    /**
-     * Gets the potion type.
-     *
-     * @return the potion type
-     */
-    @Nullable
     public PotionType getPotionType() {
         return potionType;
     }
 
-    /**
-     * Changes the potion type.
-     *
-     * @param potionType the new potion type
-     */
-    public void setPotionType(@Nullable PotionType potionType) {
-        this.potionType = potionType;
-    }
-
-    /**
-     * Get a list of {@link CustomPotionEffect}.
-     *
-     * @return the custom potion effect list
-     */
-    @NotNull
     public List<CustomPotionEffect> getCustomPotionEffects() {
         return customPotionEffects;
     }
 
-    /**
+    public Color getColor() {
-     * Changes the color of the potion.
+        return color;
-     *
-     * @param color the new color of the potion
-     * @deprecated Use {@link #setColor(Color)}
-     */
-    @Deprecated
-    public void setColor(ChatColor color) {
-        this.setColor(color.asColor());
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Changes the color of the potion.
-     *
-     * @param color the new color of the potion
-     */
-    public void setColor(@Nullable Color color) {
-        this.color = color;
-    }
 
-    @Override
+        private PotionType potionType;
-    public boolean hasNbt() {
+        private List<CustomPotionEffect> customPotionEffects = new ArrayList<>();
-        return potionType != null ||
+        private Color color;
-                !customPotionEffects.isEmpty();
-    }
 
-    @Override
+        public Builder potionType(@NotNull PotionType potionType) {
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+            this.potionType = potionType;
-        if (!(itemMeta instanceof PotionMeta))
+            this.nbt.setString("Potion", potionType.getNamespaceID());
-            return false;
+            return this;
-        PotionMeta potionMeta = (PotionMeta) itemMeta;
-        return potionMeta.potionType == potionType &&
-                potionMeta.customPotionEffects.equals(customPotionEffects) &&
-                potionMeta.color.equals(color);
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("Potion")) {
-            this.potionType = Registries.getPotionType(compound.getString("Potion"));
         }
 
-        if (compound.containsKey("CustomPotionEffects")) {
+        public Builder effects(@NotNull List<CustomPotionEffect> customPotionEffects) {
-            NBTList<NBTCompound> customEffectList = compound.getList("CustomPotionEffects");
+            this.customPotionEffects = customPotionEffects;
-            for (NBTCompound potionCompound : customEffectList) {
-                final byte id = potionCompound.getAsByte("Id");
-                final byte amplifier = potionCompound.getAsByte("Amplifier");
-                final int duration = potionCompound.containsKey("Duration") ? potionCompound.getNumber("Duration").intValue() : (int) TimeUnit.SECOND.toMilliseconds(30);
-                final boolean ambient = potionCompound.containsKey("Ambient") ? potionCompound.getAsByte("Ambient") == 1 : false;
-                final boolean showParticles = potionCompound.containsKey("ShowParticles") ? potionCompound.getAsByte("ShowParticles") == 1 : true;
-                final boolean showIcon = potionCompound.containsKey("ShowIcon") ? potionCompound.getAsByte("ShowIcon") == 1 : true;
 
-                this.customPotionEffects.add(
-                        new CustomPotionEffect(id, amplifier, duration, ambient, showParticles, showIcon));
-            }
-        }
-
-        if (compound.containsKey("CustomPotionColor")) {
-            this.color = new Color(compound.getInt("CustomPotionColor"));
-        }
-    }
-
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        if (potionType != null) {
-            compound.setString("Potion", potionType.getNamespaceID());
-        }
-        if (!customPotionEffects.isEmpty()) {
             NBTList<NBTCompound> potionList = new NBTList<>(NBTTypes.TAG_Compound);
-
             for (CustomPotionEffect customPotionEffect : customPotionEffects) {
                 NBTCompound potionCompound = new NBTCompound();
                 potionCompound.setByte("Id", customPotionEffect.getId());
@@ -142,25 +71,52 @@ public class PotionMeta extends ItemMeta {
 
                 potionList.add(potionCompound);
             }
+            this.nbt.set("CustomPotionEffects", potionList);
 
-            compound.set("CustomPotionEffects", potionList);
+            return this;
         }
 
-        if (color != null) {
+        public Builder color(@NotNull Color color) {
-            compound.setInt("CustomPotionColor", color.asRGB());
+            this.color = color;
+            this.nbt.setInt("CustomPotionColor", color.asRGB());
+            return this;
         }
 
+        @Override
+        public @NotNull PotionMeta build() {
+            return new PotionMeta(this, potionType, customPotionEffects, color);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("Potion")) {
+                potionType(Registries.getPotionType(nbtCompound.getString("Potion")));
+            }
+
+            if (nbtCompound.containsKey("CustomPotionEffects")) {
+                NBTList<NBTCompound> customEffectList = nbtCompound.getList("CustomPotionEffects");
+                for (NBTCompound potionCompound : customEffectList) {
+                    final byte id = potionCompound.getAsByte("Id");
+                    final byte amplifier = potionCompound.getAsByte("Amplifier");
+                    final int duration = potionCompound.containsKey("Duration") ? potionCompound.getNumber("Duration").intValue() : (int) TimeUnit.SECOND.toMilliseconds(30);
+                    final boolean ambient = potionCompound.containsKey("Ambient") ? potionCompound.getAsByte("Ambient") == 1 : false;
+                    final boolean showParticles = potionCompound.containsKey("ShowParticles") ? potionCompound.getAsByte("ShowParticles") == 1 : true;
+                    final boolean showIcon = potionCompound.containsKey("ShowIcon") ? potionCompound.getAsByte("ShowIcon") == 1 : true;
+
+                    this.customPotionEffects.add(
+                            new CustomPotionEffect(id, amplifier, duration, ambient, showParticles, showIcon));
+                }
+                effects(customPotionEffects);
+            }
+
+            if (nbtCompound.containsKey("CustomPotionColor")) {
+                color(new Color(nbtCompound.getInt("CustomPotionColor")));
+            }
+        }
+
+        @Override
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
     }
-
+}
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        PotionMeta potionMeta = (PotionMeta) super.clone();
-        potionMeta.potionType = potionType;
-        potionMeta.customPotionEffects = CloneUtils.cloneCopyOnWriteArrayList(customPotionEffects);
-
-        potionMeta.color = color;
-
-        return potionMeta;
-    }
-}

src/main/java/net/minestom/server/item/metadata/SpawnEggMeta.java

@@ -1,50 +1,50 @@
 package net.minestom.server.item.metadata;
 
 import net.minestom.server.entity.EntityType;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
-// TODO for which item
+import java.util.function.Supplier;
-public class SpawnEggMeta extends ItemMeta {
 
-    private EntityType entityType;
+public class SpawnEggMeta extends ItemMeta implements ItemMetaBuilder.Provider<SpawnEggMeta.Builder> {
 
-    @Override
+    private final EntityType entityType;
-    public boolean hasNbt() {
+
-        return entityType != null;
+    protected SpawnEggMeta(@NotNull ItemMetaBuilder metaBuilder, @Nullable EntityType entityType) {
+        super(metaBuilder);
+        this.entityType = entityType;
     }
 
-    @Override
+    public @Nullable EntityType getEntityType() {
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+        return entityType;
-        if (!(itemMeta instanceof SpawnEggMeta))
-            return false;
-        final SpawnEggMeta spawnEggMeta = (SpawnEggMeta) itemMeta;
-        return spawnEggMeta.entityType == entityType;
     }
 
-    @Override
+    public static class Builder extends ItemMetaBuilder {
-    public void read(@NotNull NBTCompound compound) {
+
-        if (compound.containsKey("EntityTag")) {
+        private EntityType entityType;
+
+        public Builder entityType(@Nullable EntityType entityType) {
+            this.entityType = entityType;
+            // TODO nbt
+            return this;
+        }
+
+        @Override
+        public @NotNull SpawnEggMeta build() {
+            return new SpawnEggMeta(this, entityType);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
             // TODO
         }
-    }
 
-    @Override
+        @Override
-    public void write(@NotNull NBTCompound compound) {
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-        if (!hasNbt())
+            return Builder::new;
-            return;
-        NBTCompound entityCompound = new NBTCompound();
-        if (entityType != null) {
-            entityCompound.setString("id", entityType.getNamespaceID());
         }
-
     }
-
+}
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        SpawnEggMeta spawnEggMeta = (SpawnEggMeta) super.clone();
-        spawnEggMeta.entityType = entityType;
-        return spawnEggMeta;
-    }
-}

src/main/java/net/minestom/server/item/metadata/WritableBookMeta.java

@@ -3,6 +3,8 @@ package net.minestom.server.item.metadata;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
 import net.minestom.server.adventure.AdventureSerializer;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
@@ -11,110 +13,97 @@ import org.jglrxavpok.hephaistos.nbt.NBTString;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
+import java.util.function.Supplier;
 
-public class WritableBookMeta extends ItemMeta {
+public class WritableBookMeta extends ItemMeta implements ItemMetaBuilder.Provider<WritableBookMeta.Builder> {
 
-    private String title;
+    private final String author;
-    private String author;
+    private final String title;
-    private List<Component> pages = new ArrayList<>();
+    private final List<Component> pages;
 
-    @Nullable
+    protected WritableBookMeta(@NotNull ItemMetaBuilder metaBuilder,
-    public String getTitle() {
+                               @Nullable String author, @Nullable String title,
-        return title;
+                               @NotNull List<@NotNull Component> pages) {
-    }
+        super(metaBuilder);
-
+        this.author = author;
-    public void setTitle(@Nullable String title) {
         this.title = title;
+        this.pages = new ArrayList<>(pages);
     }
 
-    @Nullable
+    public @Nullable String getAuthor() {
-    public String getAuthor() {
         return author;
     }
 
-    public void setAuthor(@Nullable String author) {
+    public @Nullable String getTitle() {
-        this.author = author;
+        return title;
     }
 
-    /**
+    public @NotNull List<@NotNull Component> getPages() {
-     * Gets an array list containing the book pages.
+        return Collections.unmodifiableList(pages);
-     * <p>
-     * The list is modifiable.
-     *
-     * @return a modifiable {@link ArrayList} containing the book pages
-     */
-    @NotNull
-    public List<Component> getPages() {
-        return pages;
     }
 
-    /**
+    public static class Builder extends ItemMetaBuilder {
-     * Sets the pages list of this book.
-     *
-     * @param pages the pages list
-     */
-    public void setPages(@NotNull List<Component> pages) {
-        this.pages = pages;
-    }
 
-    @Override
+        private String author;
-    public boolean hasNbt() {
+        private String title;
-        return !pages.isEmpty();
+        private List<Component> pages = new ArrayList<>();
-    }
 
-    @Override
+        public Builder author(@Nullable String author) {
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
+            this.author = author;
-        if (!(itemMeta instanceof WritableBookMeta))
+            handleNullable(author, "author", nbt,
-            return false;
+                    () -> new NBTString(Objects.requireNonNull(author)));
-        final WritableBookMeta writableBookMeta = (WritableBookMeta) itemMeta;
+            return this;
-        return writableBookMeta.pages.equals(pages);
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-
-        if (compound.containsKey("title")) {
-            this.title = compound.getString("title");
         }
 
-        if (compound.containsKey("author")) {
+        public Builder title(@Nullable String title) {
-            this.author = compound.getString("author");
+            this.title = title;
+            handleNullable(title, "title", nbt,
+                    () -> new NBTString(Objects.requireNonNull(title)));
+            return this;
         }
 
-        if (compound.containsKey("pages")) {
+        public Builder pages(@NotNull List<@NotNull Component> pages) {
-            final NBTList<NBTString> list = compound.getList("pages");
+            this.pages = pages;
-            for (NBTString page : list) {
+
-                this.pages.add(GsonComponentSerializer.gson().deserialize(page.getValue()));
+            handleCollection(pages, "pages", nbt, () -> {
+                NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
+                for (Component page : pages) {
+                    list.add(new NBTString(AdventureSerializer.serialize(page)));
+                }
+                return list;
+            });
+
+            return this;
+        }
+
+        @Override
+        public @NotNull WritableBookMeta build() {
+            return new WritableBookMeta(this, author, title, pages);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("author")) {
+                author(nbtCompound.getString("author"));
+            }
+            if (nbtCompound.containsKey("title")) {
+                title(nbtCompound.getString("title"));
+            }
+            if (nbtCompound.containsKey("pages")) {
+                final NBTList<NBTString> list = nbtCompound.getList("pages");
+                for (NBTString page : list) {
+                    this.pages.add(GsonComponentSerializer.gson().deserialize(page.getValue()));
+                }
+                pages(pages);
             }
         }
-    }
 
-    @Override
+        @Override
-    public void write(@NotNull NBTCompound compound) {
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
-
+            return WritableBookMeta.Builder::new;
-        if (title != null) {
-            compound.setString("title", title);
-        }
-
-        if (author != null) {
-            compound.setString("author", author);
-        }
-
-        if (!pages.isEmpty()) {
-            NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
-            for (Component page : pages) {
-                list.add(new NBTString(AdventureSerializer.serialize(page)));
-            }
-            compound.set("pages", list);
         }
     }
-
+}
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        WritableBookMeta writableBookMeta = (WritableBookMeta) super.clone();
-        writableBookMeta.pages = new ArrayList<>(pages);
-        return writableBookMeta;
-    }
-}

src/main/java/net/minestom/server/item/metadata/WrittenBookMeta.java

@@ -5,192 +5,53 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
 import net.minestom.server.adventure.AdventureSerializer;
 import net.minestom.server.adventure.Localizable;
+import net.minestom.server.item.ItemMeta;
+import net.minestom.server.item.ItemMetaBuilder;
 import org.jetbrains.annotations.NotNull;
-import org.jglrxavpok.hephaistos.nbt.NBTCompound;
+import org.jetbrains.annotations.Nullable;
-import org.jglrxavpok.hephaistos.nbt.NBTList;
+import org.jglrxavpok.hephaistos.nbt.*;
-import org.jglrxavpok.hephaistos.nbt.NBTString;
-import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
-import java.util.ArrayList;
+import java.util.*;
-import java.util.List;
+import java.util.function.Supplier;
 
-public class WrittenBookMeta extends ItemMeta {
+public class WrittenBookMeta extends ItemMeta implements ItemMetaBuilder.Provider<WrittenBookMeta.Builder> {
 
-    private boolean resolved;
+    private final boolean resolved;
-    private WrittenBookGeneration generation;
+    private final WrittenBookGeneration generation;
-    private String author;
+    private final String author;
-    private String title;
+    private final String title;
-    private List<Component> pages = new ArrayList<>();
+    private final List<Component> pages;
+
+    protected WrittenBookMeta(@NotNull ItemMetaBuilder metaBuilder, boolean resolved,
+                              @Nullable WrittenBookGeneration generation,
+                              @Nullable String author, @Nullable String title,
+                              @NotNull List<@NotNull Component> pages) {
+        super(metaBuilder);
+        this.resolved = resolved;
+        this.generation = generation;
+        this.author = author;
+        this.title = title;
+        this.pages = new ArrayList<>(pages);
+    }
 
-    /**
-     * Gets if the book is resolved.
-     *
-     * @return true if the book is resolved, false otherwise
-     */
     public boolean isResolved() {
         return resolved;
     }
 
-    /**
+    public @Nullable WrittenBookGeneration getGeneration() {
-     * Sets to true when the book (or a book from the stack)
-     * is opened for the first time after being created.
-     *
-     * @param resolved true to make the book resolved, false otherwise
-     */
-    public void setResolved(boolean resolved) {
-        this.resolved = resolved;
-    }
-
-    /**
-     * Gets the copy tier of the book.
-     *
-     * @return the copy tier of the book
-     */
-    public WrittenBookGeneration getGeneration() {
         return generation;
     }
 
-    /**
+    public @Nullable String getAuthor() {
-     * Sets the copy tier of the book.
-     *
-     * @param generation the copy tier of the book
-     */
-    public void setGeneration(WrittenBookGeneration generation) {
-        this.generation = generation;
-    }
-
-    /**
-     * Gets the author of the book.
-     *
-     * @return the author of the book
-     */
-    public String getAuthor() {
         return author;
     }
 
-    /**
+    public @Nullable String getTitle() {
-     * Sets the author of the book.
-     *
-     * @param author the author of the book
-     */
-    public void setAuthor(String author) {
-        this.author = author;
-    }
-
-    /**
-     * Gets the title of the book.
-     *
-     * @return the title of the book
-     */
-    public String getTitle() {
         return title;
     }
 
-    /**
+    public @NotNull List<@NotNull Component> getPages() {
-     * Sets the title of the book.
+        return Collections.unmodifiableList(pages);
-     *
-     * @param title the title of the book
-     */
-    public void setTitle(String title) {
-        this.title = title;
-    }
-
-    /**
-     * Gets an {@link ArrayList} containing all the pages.
-     * <p>
-     * The list is not modifiable as it is .
-     *
-     * @return a modifiable {@link ArrayList} with the pages of the book
-     */
-    @Deprecated
-    public List<Component> getPagesJson() {
-        return pages;
-    }
-
-    /**
-     * Sets the {@link ArrayList} containing the book pages.
-     *
-     * @param pages the array list containing the book pages
-     */
-    public void setPages(List<Component> pages) {
-        this.pages = pages;
-    }
-
-    @Override
-    public boolean hasNbt() {
-        return resolved || generation != null ||
-                author != null || title != null ||
-                !pages.isEmpty();
-    }
-
-    @Override
-    public boolean isSimilar(@NotNull ItemMeta itemMeta) {
-        if (!(itemMeta instanceof WrittenBookMeta))
-            return false;
-        final WrittenBookMeta writtenBookMeta = (WrittenBookMeta) itemMeta;
-        return writtenBookMeta.resolved == resolved &&
-                writtenBookMeta.generation == generation &&
-                writtenBookMeta.author.equals(author) &&
-                writtenBookMeta.title.equals(title) &&
-                writtenBookMeta.pages.equals(pages);
-    }
-
-    @Override
-    public void read(@NotNull NBTCompound compound) {
-        if (compound.containsKey("resolved")) {
-            this.resolved = compound.getByte("resolved") == 1;
-        }
-        if (compound.containsKey("generation")) {
-            this.generation = WrittenBookGeneration.values()[compound.getInt("generation")];
-        }
-        if (compound.containsKey("author")) {
-            this.author = compound.getString("author");
-        }
-        if (compound.containsKey("title")) {
-            this.title = compound.getString("title");
-        }
-        if (compound.containsKey("pages")) {
-            final NBTList<NBTString> list = compound.getList("pages");
-            for (NBTString page : list) {
-                this.pages.add(GsonComponentSerializer.gson().deserialize(page.getValue()));
-            }
-        }
-    }
-
-    @Override
-    public void write(@NotNull NBTCompound compound) {
-        if (resolved) {
-            compound.setByte("resolved", (byte) 1);
-        }
-        if (generation != null) {
-            compound.setInt("generation", generation.ordinal());
-        }
-        if (author != null) {
-            compound.setString("author", author);
-        }
-        if (title != null) {
-            compound.setString("title", title);
-        }
-        if (!pages.isEmpty()) {
-            NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
-            for (Component page : pages) {
-                list.add(new NBTString(AdventureSerializer.serialize(page)));
-            }
-            compound.set("pages", list);
-        }
-    }
-
-    @NotNull
-    @Override
-    public ItemMeta clone() {
-        WrittenBookMeta writtenBookMeta = (WrittenBookMeta) super.clone();
-        writtenBookMeta.resolved = resolved;
-        writtenBookMeta.generation = generation;
-        writtenBookMeta.author = author;
-        writtenBookMeta.title = title;
-        writtenBookMeta.pages.addAll(pages);
-
-        return writtenBookMeta;
     }
 
     public enum WrittenBookGeneration {
@@ -201,21 +62,104 @@ public class WrittenBookMeta extends ItemMeta {
      * Creates a written book meta from an Adventure book. This meta will not be
      * resolved and the generation will default to {@link WrittenBookGeneration#ORIGINAL}.
      *
-     * @param book the book
+     * @param book        the book
      * @param localizable who the book is for
-     *
      * @return the meta
      */
     public static @NotNull WrittenBookMeta fromAdventure(@NotNull Book book, @NotNull Localizable localizable) {
-        // make the book
+        return new Builder()
-        WrittenBookMeta meta = new WrittenBookMeta();
+                .resolved(false)
-        meta.resolved = false;
+                .generation(WrittenBookGeneration.ORIGINAL)
-        meta.generation = WrittenBookGeneration.ORIGINAL;
+                .author(AdventureSerializer.translateAndSerialize(book.author(), localizable))
-        meta.author = AdventureSerializer.translateAndSerialize(book.author(), localizable);
+                .title(AdventureSerializer.translateAndSerialize(book.title(), localizable))
-        meta.title = AdventureSerializer.translateAndSerialize(book.title(), localizable);
+                .pages(book.pages())
-        meta.pages = new ArrayList<>();
+                .build();
-        meta.pages.addAll(book.pages());
+    }
 
-        return meta;
+    public static class Builder extends ItemMetaBuilder {
+
+        private boolean resolved;
+        private WrittenBookGeneration generation;
+        private String author;
+        private String title;
+        private List<Component> pages = new ArrayList<>();
+
+        public Builder resolved(boolean resolved) {
+            this.resolved = resolved;
+            this.nbt.setByte("resolved", (byte) (resolved ? 1 : 0));
+            return this;
+        }
+
+        public Builder generation(@Nullable WrittenBookGeneration generation) {
+            this.generation = generation;
+            handleNullable(generation, "generation", nbt,
+                    () -> new NBTInt(Objects.requireNonNull(generation).ordinal()));
+            return this;
+        }
+
+        public Builder author(@Nullable String author) {
+            this.author = author;
+            handleNullable(author, "author", nbt,
+                    () -> new NBTString(Objects.requireNonNull(author)));
+            return this;
+        }
+
+        public Builder title(@Nullable String title) {
+            this.title = title;
+            handleNullable(title, "title", nbt,
+                    () -> new NBTString(Objects.requireNonNull(title)));
+            return this;
+        }
+
+        public Builder pages(@NotNull List<@NotNull Component> pages) {
+            this.pages = pages;
+
+            handleCollection(pages, "pages", nbt, () -> {
+                NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
+                for (Component page : pages) {
+                    list.add(new NBTString(AdventureSerializer.serialize(page)));
+                }
+                return list;
+            });
+
+            return this;
+        }
+
+        public Builder pages(Component... pages) {
+            return pages(Arrays.asList(pages));
+        }
+
+        @Override
+        public @NotNull WrittenBookMeta build() {
+            return new WrittenBookMeta(this, resolved, generation, author, title, pages);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            if (nbtCompound.containsKey("resolved")) {
+                resolved(nbtCompound.getByte("resolved") == 1);
+            }
+            if (nbtCompound.containsKey("generation")) {
+                generation(WrittenBookGeneration.values()[nbtCompound.getInt("generation")]);
+            }
+            if (nbtCompound.containsKey("author")) {
+                author(nbtCompound.getString("author"));
+            }
+            if (nbtCompound.containsKey("title")) {
+                title(nbtCompound.getString("title"));
+            }
+            if (nbtCompound.containsKey("pages")) {
+                final NBTList<NBTString> list = nbtCompound.getList("pages");
+                for (NBTString page : list) {
+                    this.pages.add(GsonComponentSerializer.gson().deserialize(page.getValue()));
+                }
+                pages(pages);
+            }
+        }
+
+        @Override
+        protected @NotNull Supplier<ItemMetaBuilder> getSupplier() {
+            return Builder::new;
+        }
     }
 }

src/main/java/net/minestom/server/item/rule/VanillaStackingRule.java

@@ -25,10 +25,9 @@ public class VanillaStackingRule extends StackingRule {
     @Override
     public ItemStack apply(@NotNull ItemStack item, int newAmount) {
         if (newAmount <= 0)
-            return ItemStack.getAirItem();
+            return ItemStack.AIR;
 
-        item.setAmount((byte) newAmount);
+        return item.withAmount(newAmount);
-        return item;
     }
 
     @Override

src/main/java/net/minestom/server/listener/AnimationListener.java

@@ -10,7 +10,7 @@ public class AnimationListener {
     public static void animationListener(ClientAnimationPacket packet, Player player) {
         final Player.Hand hand = packet.hand;
         final ItemStack itemStack = player.getItemInHand(hand);
-        itemStack.onLeftClick(player, hand);
+        //itemStack.onLeftClick(player, hand);
         PlayerHandAnimationEvent handAnimationEvent = new PlayerHandAnimationEvent(player, hand);
         player.callCancellableEvent(PlayerHandAnimationEvent.class, handAnimationEvent, () -> {
             switch (hand) {

src/main/java/net/minestom/server/listener/BlockPlacementListener.java

@@ -52,7 +52,8 @@ public class BlockPlacementListener {
         final ItemStack usedItem = player.getItemInHand(hand);
 
         // Interact at block
-        final boolean cancel = usedItem.onUseOnBlock(player, hand, blockPosition, direction);
+        // FIXME: onUseOnBlock
+        final boolean cancel = false;//usedItem.onUseOnBlock(player, hand, blockPosition, direction);
         PlayerBlockInteractEvent playerBlockInteractEvent = new PlayerBlockInteractEvent(player, blockPosition, hand, blockFace);
         playerBlockInteractEvent.setCancelled(cancel);
         playerBlockInteractEvent.setBlockingItemUse(cancel);
@@ -85,7 +86,8 @@ public class BlockPlacementListener {
                 canPlaceBlock = false; //Spectators can't place blocks
             } else if (player.getGameMode() == GameMode.ADVENTURE) {
                 //Check if the block can placed on the block
-                canPlaceBlock = usedItem.canPlaceOn(instance.getBlock(blockPosition).getName());
+                Block placeBlock = instance.getBlock(blockPosition);
+                canPlaceBlock = usedItem.getMeta().getCanPlaceOn().contains(placeBlock);
             }
         }
 
@@ -166,11 +168,8 @@ public class BlockPlacementListener {
                             // Block consuming
                             if (playerBlockPlaceEvent.doesConsumeBlock()) {
                                 // Consume the block in the player's hand
-                                final ItemStack newUsedItem = usedItem.consume(1);
+                                final ItemStack newUsedItem = usedItem.getStackingRule().apply(usedItem, usedItem.getAmount() - 1);
-
+                                playerInventory.setItemInHand(hand, newUsedItem);
-                                if (newUsedItem != null) {
-                                    playerInventory.setItemInHand(hand, newUsedItem);
-                                }
                             }
                         } else {
                             refreshChunk = true;
@@ -196,8 +195,6 @@ public class BlockPlacementListener {
         if (refreshChunk) {
             chunk.sendChunkSectionUpdate(ChunkUtils.getSectionAt(blockPosition.getY()), player);
         }
-
-        player.getInventory().refreshSlot(player.getHeldSlot());
     }
 
 }

src/main/java/net/minestom/server/listener/PlayerDiggingListener.java

@@ -47,7 +47,8 @@ public class PlayerDiggingListener {
             } else if (player.getGameMode() == GameMode.ADVENTURE) {
                 //Check if the item can break the block with the current item
                 ItemStack itemInMainHand = player.getItemInMainHand();
-                if (!itemInMainHand.canDestroy(instance.getBlock(blockPosition).getName())) {
+                Block destroyedBlock = instance.getBlock(blockPosition);
+                if (!itemInMainHand.getMeta().getCanDestroy().contains(destroyedBlock)) {
                     sendAcknowledgePacket(player, blockPosition, blockStateId,
                             ClientPlayerDiggingPacket.Status.STARTED_DIGGING, false);
                     return;
@@ -111,7 +112,7 @@ public class PlayerDiggingListener {
         } else if (status == ClientPlayerDiggingPacket.Status.DROP_ITEM_STACK) {
 
             final ItemStack droppedItemStack = player.getInventory().getItemInMainHand();
-            dropItem(player, droppedItemStack, ItemStack.getAirItem());
+            dropItem(player, droppedItemStack, ItemStack.AIR);
 
         } else if (status == ClientPlayerDiggingPacket.Status.DROP_ITEM) {
 
@@ -123,14 +124,11 @@ public class PlayerDiggingListener {
 
             if (handAmount <= dropAmount) {
                 // Drop the whole item without copy
-                dropItem(player, handItem, ItemStack.getAirItem());
+                dropItem(player, handItem, ItemStack.AIR);
             } else {
                 // Drop a single item, need a copy
-                ItemStack droppedItemStack2 = handItem.clone();
+                ItemStack droppedItemStack2 = stackingRule.apply(handItem, dropAmount);
 
-                droppedItemStack2 = stackingRule.apply(droppedItemStack2, dropAmount);
-
-                handItem = handItem.clone(); // Force the copy
                 handItem = stackingRule.apply(handItem, handAmount - dropAmount);
 
                 dropItem(player, droppedItemStack2, handItem);

src/main/java/net/minestom/server/listener/UseItemListener.java

@@ -15,7 +15,7 @@ public class UseItemListener {
         final PlayerInventory inventory = player.getInventory();
         final Player.Hand hand = packet.hand;
         ItemStack itemStack = hand == Player.Hand.MAIN ? inventory.getItemInMainHand() : inventory.getItemInOffHand();
-        itemStack.onRightClick(player, hand);
+        //itemStack.onRightClick(player, hand);
         PlayerUseItemEvent useItemEvent = new PlayerUseItemEvent(player, hand, itemStack);
         player.callEvent(PlayerUseItemEvent.class, useItemEvent);
 

src/main/java/net/minestom/server/network/packet/client/play/ClientClickWindowPacket.java

@@ -13,7 +13,7 @@ public class ClientClickWindowPacket extends ClientPlayPacket {
     public byte button;
     public short actionNumber;
     public int mode;
-    public ItemStack item = ItemStack.getAirItem();
+    public ItemStack item = ItemStack.AIR;
 
     @Override
     public void read(@NotNull BinaryReader reader) {

src/main/java/net/minestom/server/network/packet/client/play/ClientCreativeInventoryActionPacket.java

@@ -9,7 +9,7 @@ import org.jetbrains.annotations.NotNull;
 public class ClientCreativeInventoryActionPacket extends ClientPlayPacket {
 
     public short slot;
-    public ItemStack item = ItemStack.getAirItem();
+    public ItemStack item = ItemStack.AIR;
 
     @Override
     public void read(@NotNull BinaryReader reader) {

src/main/java/net/minestom/server/network/packet/client/play/ClientEditBookPacket.java

@@ -9,7 +9,7 @@ import org.jetbrains.annotations.NotNull;
 
 public class ClientEditBookPacket extends ClientPlayPacket {
 
-    public ItemStack book = ItemStack.getAirItem();
+    public ItemStack book = ItemStack.AIR;
     public boolean isSigning;
     public Player.Hand hand = Player.Hand.MAIN;
 

src/main/java/net/minestom/server/network/packet/client/play/ClientNameItemPacket.java

@@ -17,7 +17,7 @@ public class ClientNameItemPacket extends ClientPlayPacket {
     @Override
     public void write(@NotNull BinaryWriter writer) {
         if(itemName.length() > Short.MAX_VALUE) {
-            throw new IllegalArgumentException("Item name cannot be longer than Short.MAX_VALUE characters!");
+            throw new IllegalArgumentException("ItemStack name cannot be longer than Short.MAX_VALUE characters!");
         }
         writer.writeSizedString(itemName);
     }

src/main/java/net/minestom/server/network/packet/server/play/AdvancementsPacket.java

@@ -25,7 +25,8 @@ public class AdvancementsPacket implements ComponentHoldingServerPacket {
     public String[] identifiersToRemove = new String[0];
     public ProgressMapping[] progressMappings = new ProgressMapping[0];
 
-    public AdvancementsPacket() {}
+    public AdvancementsPacket() {
+    }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
@@ -149,14 +150,14 @@ public class AdvancementsPacket implements ComponentHoldingServerPacket {
         @Override
         public void read(@NotNull BinaryReader reader) {
             boolean hasParent = reader.readBoolean();
-            if(hasParent) {
+            if (hasParent) {
                 parentIdentifier = reader.readSizedString(Integer.MAX_VALUE);
             } else {
                 parentIdentifier = null;
             }
 
             boolean hasDisplay = reader.readBoolean();
-            if(hasDisplay) {
+            if (hasDisplay) {
                 displayData = new DisplayData();
                 displayData.read(reader);
             } else {
@@ -177,7 +178,7 @@ public class AdvancementsPacket implements ComponentHoldingServerPacket {
     public static class DisplayData implements Writeable, Readable {
         public Component title = Component.empty(); // Only text
         public Component description = Component.empty(); // Only text
-        public ItemStack icon = ItemStack.getAirItem();
+        public ItemStack icon = ItemStack.AIR;
         public FrameType frameType = FrameType.TASK;
         public int flags;
         public String backgroundTexture = "";
@@ -205,7 +206,7 @@ public class AdvancementsPacket implements ComponentHoldingServerPacket {
             icon = reader.readItemStack();
             frameType = FrameType.values()[reader.readVarInt()];
             flags = reader.readInt();
-            if((flags & 0x1) != 0) {
+            if ((flags & 0x1) != 0) {
                 backgroundTexture = reader.readSizedString(Integer.MAX_VALUE);
             } else {
                 backgroundTexture = null;
@@ -302,7 +303,7 @@ public class AdvancementsPacket implements ComponentHoldingServerPacket {
         @Override
         public void read(@NotNull BinaryReader reader) {
             achieved = reader.readBoolean();
-            if(achieved) {
+            if (achieved) {
                 dateOfAchieving = reader.readLong();
             }
         }

src/main/java/net/minestom/server/network/packet/server/play/DeclareRecipesPacket.java

@@ -14,7 +14,8 @@ public class DeclareRecipesPacket implements ServerPacket {
 
     public DeclaredRecipe[] recipes = new DeclaredRecipe[0];
 
-    public DeclareRecipesPacket() {}
+    public DeclareRecipesPacket() {
+    }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
@@ -68,7 +69,7 @@ public class DeclareRecipesPacket implements ServerPacket {
                     break;
 
                 default:
-                    throw new UnsupportedOperationException("Unrecognized type: "+type+" (id is "+id+")");
+                    throw new UnsupportedOperationException("Unrecognized type: " + type + " (id is " + id + ")");
             }
         }
     }
@@ -193,7 +194,7 @@ public class DeclareRecipesPacket implements ServerPacket {
             width = reader.readVarInt();
             height = reader.readVarInt();
             group = reader.readSizedString(Integer.MAX_VALUE);
-            ingredients = new Ingredient[width*height];
+            ingredients = new Ingredient[width * height];
             for (int i = 0; i < width * height; i++) {
                 ingredients[i] = new Ingredient();
                 ingredients[i].read(reader);
@@ -442,7 +443,7 @@ public class DeclareRecipesPacket implements ServerPacket {
         public void read(@NotNull BinaryReader reader) {
             group = reader.readSizedString(Integer.MAX_VALUE);
             ingredient = new Ingredient();
-            ingredient.read( reader);
+            ingredient.read(reader);
             result = reader.readItemStack();
         }
     }

src/main/java/net/minestom/server/network/packet/server/play/EntityEquipmentPacket.java

@@ -17,7 +17,8 @@ public class EntityEquipmentPacket implements ServerPacket {
     public Slot[] slots;
     public ItemStack[] itemStacks;
 
-    public EntityEquipmentPacket() {}
+    public EntityEquipmentPacket() {
+    }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
@@ -53,7 +54,7 @@ public class EntityEquipmentPacket implements ServerPacket {
         boolean hasRemaining = true;
         List<Slot> slots = new LinkedList<>();
         List<ItemStack> stacks = new LinkedList<>();
-        while(hasRemaining) {
+        while (hasRemaining) {
             byte slotEnum = reader.readByte();
             hasRemaining = (slotEnum & 0x80) == 0x80;
 

src/main/java/net/minestom/server/network/packet/server/play/OpenWindowPacket.java

@@ -1,7 +1,6 @@
 package net.minestom.server.network.packet.server.play;
 
-import net.minestom.server.chat.ColoredText;
+import net.kyori.adventure.text.Component;
-import net.minestom.server.chat.JsonMessage;
 import net.minestom.server.network.packet.server.ServerPacket;
 import net.minestom.server.network.packet.server.ServerPacketIdentifier;
 import net.minestom.server.utils.binary.BinaryReader;
@@ -12,26 +11,27 @@ public class OpenWindowPacket implements ServerPacket {
 
     public int windowId;
     public int windowType;
-    public JsonMessage title = ColoredText.of("");
+    public Component title = Component.text("");
 
-    public OpenWindowPacket() {}
+    public OpenWindowPacket() {
+    }
 
-    public OpenWindowPacket(String title) {
+    public OpenWindowPacket(Component title) {
-        this.title = ColoredText.of(title);
+        this.title = title;
     }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
         writer.writeVarInt(windowId);
         writer.writeVarInt(windowType);
-        writer.writeJsonMessage(title);
+        writer.writeComponent(title);
     }
 
     @Override
     public void read(@NotNull BinaryReader reader) {
         windowId = reader.readVarInt();
         windowType = reader.readVarInt();
-        title = reader.readJsonMessage(Integer.MAX_VALUE);
+        title = reader.readComponent(Integer.MAX_VALUE);
     }
 
     @Override

src/main/java/net/minestom/server/network/packet/server/play/SetSlotPacket.java

@@ -14,7 +14,7 @@ public class SetSlotPacket implements ServerPacket {
     public ItemStack itemStack;
 
     public SetSlotPacket() {
-        itemStack = ItemStack.getAirItem();
+        itemStack = ItemStack.AIR;
     }
 
     @Override

src/main/java/net/minestom/server/network/packet/server/play/TradeListPacket.java

@@ -96,7 +96,7 @@ public class TradeListPacket implements ServerPacket {
             result = reader.readItemStack();
 
             boolean hasSecondItem = reader.readBoolean();
-            if(hasSecondItem) {
+            if (hasSecondItem) {
                 inputItem2 = reader.readItemStack();
             } else {
                 inputItem2 = null;

src/main/java/net/minestom/server/recipe/ShapedRecipe.java

@@ -17,11 +17,11 @@ public abstract class ShapedRecipe extends Recipe {
     private ItemStack result;
 
     protected ShapedRecipe(@NotNull String recipeId,
-                        int width,
+                           int width,
-                        int height,
+                           int height,
-                        @NotNull String group,
+                           @NotNull String group,
-                        @Nullable List<DeclareRecipesPacket.Ingredient> ingredients,
+                           @Nullable List<DeclareRecipesPacket.Ingredient> ingredients,
-                        @NotNull ItemStack result) {
+                           @NotNull ItemStack result) {
         super(RecipeType.SHAPED, recipeId);
         this.width = width;
         this.height = height;

src/main/java/net/minestom/server/thread/ThreadProvider.java

@@ -38,7 +38,7 @@ public abstract class ThreadProvider {
 
     {
         // Default thread count in the pool (cores * 2)
-        setThreadCount(NettyRuntime.availableProcessors() * 2);
+        setThreadCount(1);
     }
 
     /**

src/main/java/net/minestom/server/utils/NBTUtils.java

@@ -5,22 +5,18 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
 import net.kyori.adventure.util.Codec;
 import net.minestom.server.MinecraftServer;
-import net.minestom.server.adventure.AdventureSerializer;
 import net.minestom.server.attribute.Attribute;
 import net.minestom.server.attribute.AttributeOperation;
-import net.minestom.server.data.Data;
+import net.minestom.server.instance.block.Block;
-import net.minestom.server.data.DataType;
 import net.minestom.server.inventory.Inventory;
 import net.minestom.server.item.Enchantment;
+import net.minestom.server.item.ItemMetaBuilder;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.item.Material;
 import net.minestom.server.item.attribute.AttributeSlot;
 import net.minestom.server.item.attribute.ItemAttribute;
-import net.minestom.server.item.metadata.ItemMeta;
 import net.minestom.server.registry.Registries;
 import net.minestom.server.utils.binary.BinaryReader;
-import net.minestom.server.utils.binary.BinaryWriter;
-import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -48,6 +44,7 @@ public final class NBTUtils {
 
     /**
      * Turns an {@link NBTCompound} into an Adventure {@link BinaryTagHolder}.
+     *
      * @param tag the tag, if any
      * @return the binary tag holder, or {@code null} if the tag was null
      */
@@ -69,15 +66,17 @@ public final class NBTUtils {
     public static void loadAllItems(@NotNull NBTList<NBTCompound> items, @NotNull Inventory destination) {
         destination.clear();
         for (NBTCompound tag : items) {
-            Material item = Registries.getMaterial(tag.getString("id"));
+            Material material = Registries.getMaterial(tag.getString("id"));
-            if (item == Material.AIR) {
+            if (material == Material.AIR) {
-                item = Material.STONE;
+                material = Material.STONE;
             }
-            ItemStack stack = new ItemStack(item, tag.getByte("Count"));
+            byte count = tag.getByte("Count");
+            NBTCompound nbtCompound = null;
             if (tag.containsKey("tag")) {
-                loadDataIntoItem(stack, tag.getCompound("tag"));
+                nbtCompound = tag.getCompound("tag");
             }
-            destination.setItemStack(tag.getByte("Slot"), stack);
+            ItemStack itemStack = loadItem(material, count, nbtCompound);
+            destination.setItemStack(tag.getByte("Slot"), itemStack);
         }
     }
 
@@ -86,12 +85,11 @@ public final class NBTUtils {
             final ItemStack stack = inventory.getItemStack(i);
             NBTCompound nbt = new NBTCompound();
 
-            NBTCompound tag = new NBTCompound();
+            NBTCompound tag = stack.getMeta().toNBT();
-            saveDataIntoNBT(stack, tag);
 
             nbt.set("tag", tag);
             nbt.setByte("Slot", (byte) i);
-            nbt.setByte("Count", stack.getAmount());
+            nbt.setByte("Count", (byte) stack.getAmount());
             nbt.setString("id", stack.getMaterial().getName());
 
             list.add(nbt);
@@ -113,48 +111,60 @@ public final class NBTUtils {
         nbt.set(listName, enchantList);
     }
 
-    @Nullable
+    @NotNull
     public static ItemStack readItemStack(@NotNull BinaryReader reader) {
         final boolean present = reader.readBoolean();
 
         if (!present) {
-            return ItemStack.getAirItem();
+            return ItemStack.AIR;
         }
 
         final int id = reader.readVarInt();
         if (id == -1) {
             // Drop mode
-            return ItemStack.getAirItem();
+            return ItemStack.AIR;
         }
 
         final Material material = Material.fromId((short) id);
         final byte count = reader.readByte();
-        ItemStack item = new ItemStack(material, count);
+        NBTCompound nbtCompound = null;
 
         try {
             final NBT itemNBT = reader.readTag();
             if (itemNBT instanceof NBTCompound) { // can also be a TAG_End if no data
-                NBTCompound nbt = (NBTCompound) itemNBT;
+                nbtCompound = (NBTCompound) itemNBT;
-                loadDataIntoItem(item, nbt);
             }
         } catch (IOException | NBTException e) {
             MinecraftServer.getExceptionManager().handleException(e);
         }
 
-        return item;
+        return loadItem(material, count, nbtCompound);
+    }
+
+    public static @NotNull ItemStack loadItem(@NotNull Material material, int count, @Nullable NBTCompound nbtCompound) {
+        return ItemStack.builder(material)
+                .amount(count)
+                .meta(metaBuilder -> {
+                    if (nbtCompound != null) {
+                        return ItemMetaBuilder.fromNBT(metaBuilder, nbtCompound);
+                    } else {
+                        return metaBuilder;
+                    }
+                })
+                .build();
     }
 
     @SuppressWarnings("ConstantConditions")
-    public static void loadDataIntoItem(@NotNull ItemStack item, @NotNull NBTCompound nbt) {
+    public static void loadDataIntoMeta(@NotNull ItemMetaBuilder metaBuilder, @NotNull NBTCompound nbt) {
-        if (nbt.containsKey("Damage")) item.setDamage(nbt.getInt("Damage"));
+        if (nbt.containsKey("Damage")) metaBuilder.damage(nbt.getInt("Damage"));
-        if (nbt.containsKey("Unbreakable")) item.setUnbreakable(nbt.getAsByte("Unbreakable") == 1);
+        if (nbt.containsKey("Unbreakable")) metaBuilder.unbreakable(nbt.getAsByte("Unbreakable") == 1);
-        if (nbt.containsKey("HideFlags")) item.setHideFlag(nbt.getInt("HideFlags"));
+        if (nbt.containsKey("HideFlags")) metaBuilder.hideFlag(nbt.getInt("HideFlags"));
         if (nbt.containsKey("display")) {
             final NBTCompound display = nbt.getCompound("display");
             if (display.containsKey("Name")) {
                 final String rawName = display.getString("Name");
                 final Component displayName = GsonComponentSerializer.gson().deserialize(rawName);
-                item.setDisplayName(displayName);
+                metaBuilder.displayName(displayName);
             }
             if (display.containsKey("Lore")) {
                 NBTList<NBTString> loreList = display.getList("Lore");
@@ -162,19 +172,20 @@ public final class NBTUtils {
                 for (NBTString s : loreList) {
                     lore.add(GsonComponentSerializer.gson().deserialize(s.getValue()));
                 }
-                item.setLore(lore);
+                metaBuilder.lore(lore);
             }
         }
 
         // Enchantments
         if (nbt.containsKey("Enchantments")) {
-            loadEnchantments(nbt.getList("Enchantments"), item::setEnchantment);
+            loadEnchantments(nbt.getList("Enchantments"), metaBuilder::enchantment);
         }
 
         // Attributes
         if (nbt.containsKey("AttributeModifiers")) {
-            NBTList<NBTCompound> attributes = nbt.getList("AttributeModifiers");
+            List<ItemAttribute> attributes = new ArrayList<>();
-            for (NBTCompound attributeNBT : attributes) {
+            NBTList<NBTCompound> nbtAttributes = nbt.getList("AttributeModifiers");
+            for (NBTCompound attributeNBT : nbtAttributes) {
                 final UUID uuid;
                 {
                     final int[] uuidArray = attributeNBT.getIntArray("UUID");
@@ -208,54 +219,43 @@ public final class NBTUtils {
                 // Add attribute
                 final ItemAttribute itemAttribute =
                         new ItemAttribute(uuid, name, attribute, attributeOperation, value, attributeSlot);
-                item.addAttribute(itemAttribute);
+                attributes.add(itemAttribute);
-            }
-        }
-
-        // Hide flags
-        {
-            if (nbt.containsKey("HideFlags")) {
-                item.setHideFlag(nbt.getInt("HideFlags"));
             }
+            metaBuilder.attributes(attributes);
         }
 
         // Custom model data
         {
             if (nbt.containsKey("CustomModelData")) {
-                item.setCustomModelData(nbt.getInt("CustomModelData"));
+                metaBuilder.customModelData(nbt.getInt("CustomModelData"));
             }
         }
 
-        // Meta specific field
+        // Meta specific fields
-        final ItemMeta itemMeta = item.getItemMeta();
+        metaBuilder.read(nbt);
-        if (itemMeta != null) {
-            itemMeta.read(nbt);
-        }
 
-        // Ownership
+        // CanPlaceOn
-        {
-            if (nbt.containsKey(ItemStack.OWNERSHIP_DATA_KEY)) {
-                final String identifierString = nbt.getString(ItemStack.OWNERSHIP_DATA_KEY);
-                final UUID identifier = UUID.fromString(identifierString);
-                final Data data = ItemStack.DATA_OWNERSHIP.getOwnObject(identifier);
-                if (data != null) {
-                    item.setData(data);
-                }
-            }
-        }
-
-        //CanPlaceOn
         {
             if (nbt.containsKey("CanPlaceOn")) {
                 NBTList<NBTString> canPlaceOn = nbt.getList("CanPlaceOn");
-                canPlaceOn.forEach(x -> item.getCanPlaceOn().add(x.getValue()));
+                Set<Block> blocks = new HashSet<>();
+                for (NBTString blockNamespace : canPlaceOn) {
+                    Block block = Registries.getBlock(blockNamespace.getValue());
+                    blocks.add(block);
+                }
+                metaBuilder.canPlaceOn(blocks);
             }
         }
-        //CanDestroy
+        // CanDestroy
         {
             if (nbt.containsKey("CanDestroy")) {
-                NBTList<NBTString> canPlaceOn = nbt.getList("CanDestroy");
+                NBTList<NBTString> canDestroy = nbt.getList("CanDestroy");
-                canPlaceOn.forEach(x -> item.getCanDestroy().add(x.getValue()));
+                Set<Block> blocks = new HashSet<>();
+                for (NBTString blockNamespace : canDestroy) {
+                    Block block = Registries.getBlock(blockNamespace.getValue());
+                    blocks.add(block);
+                }
+                metaBuilder.canDestroy(blocks);
             }
         }
     }
@@ -273,243 +273,6 @@ public final class NBTUtils {
         }
     }
 
-    public static void writeItemStack(BinaryWriter packet, ItemStack itemStack) {
-        if (itemStack == null || itemStack.isAir()) {
-            packet.writeBoolean(false);
-        } else {
-            packet.writeBoolean(true);
-            packet.writeVarInt(itemStack.getMaterial().getId());
-            packet.writeByte(itemStack.getAmount());
-
-            if (!itemStack.hasNbtTag()) {
-                packet.writeByte((byte) NBTTypes.TAG_End); // No nbt
-                return;
-            }
-
-            NBTCompound itemNBT = new NBTCompound();
-
-            // Vanilla compound
-            saveDataIntoNBT(itemStack, itemNBT);
-
-            // End custom model data
-            packet.writeNBT("", itemNBT);
-        }
-    }
-
-    public static void saveDataIntoNBT(@NotNull ItemStack itemStack, @NotNull NBTCompound itemNBT) {
-        // Unbreakable
-        if (itemStack.isUnbreakable()) {
-            itemNBT.setInt("Unbreakable", 1);
-        }
-
-        // Start damage
-        {
-            final int damage = itemStack.getDamage();
-            if (damage > 0) {
-                itemNBT.setInt("Damage", damage);
-            }
-        }
-        // End damage
-
-        // Display
-        final boolean hasDisplayName = itemStack.hasDisplayName();
-        final boolean hasLore = itemStack.hasLore();
-
-        if (hasDisplayName || hasLore) {
-            NBTCompound displayNBT = new NBTCompound();
-            if (hasDisplayName) {
-                final String name = AdventureSerializer.serialize(itemStack.getDisplayName());
-                displayNBT.setString("Name", name);
-            }
-
-            if (hasLore) {
-                final List<Component> lore = itemStack.getLore();
-
-                final NBTList<NBTString> loreNBT = new NBTList<>(NBTTypes.TAG_String);
-                for (Component line : lore) {
-                    loreNBT.add(new NBTString(GsonComponentSerializer.gson().serialize(line)));
-                }
-                displayNBT.set("Lore", loreNBT);
-            }
-
-            itemNBT.set("display", displayNBT);
-        }
-        // End display
-
-        // Start enchantment
-        {
-            final Map<Enchantment, Short> enchantmentMap = itemStack.getEnchantmentMap();
-            if (!enchantmentMap.isEmpty()) {
-                writeEnchant(itemNBT, "Enchantments", enchantmentMap);
-            }
-        }
-        // End enchantment
-
-        // Start attribute
-        {
-            final List<ItemAttribute> itemAttributes = itemStack.getAttributes();
-            if (!itemAttributes.isEmpty()) {
-                NBTList<NBTCompound> attributesNBT = new NBTList<>(NBTTypes.TAG_Compound);
-
-                for (ItemAttribute itemAttribute : itemAttributes) {
-                    final UUID uuid = itemAttribute.getUuid();
-                    attributesNBT.add(
-                            new NBTCompound()
-                                    .setIntArray("UUID", Utils.uuidToIntArray(uuid))
-                                    .setDouble("Amount", itemAttribute.getValue())
-                                    .setString("Slot", itemAttribute.getSlot().name().toLowerCase())
-                                    .setString("AttributeName", itemAttribute.getAttribute().getKey())
-                                    .setInt("Operation", itemAttribute.getOperation().getId())
-                                    .setString("Name", itemAttribute.getInternalName())
-                    );
-                }
-                itemNBT.set("AttributeModifiers", attributesNBT);
-            }
-        }
-        // End attribute
-
-        // Start hide flags
-        {
-            final int hideFlag = itemStack.getHideFlag();
-            if (hideFlag != 0) {
-                itemNBT.setInt("HideFlags", hideFlag);
-            }
-        }
-        // End hide flags
-
-        // Start custom model data
-        {
-            final int customModelData = itemStack.getCustomModelData();
-            if (customModelData != 0) {
-                itemNBT.setInt("CustomModelData", customModelData);
-            }
-        }
-        // End custom model data
-
-        // Start custom meta
-        {
-            final ItemMeta itemMeta = itemStack.getItemMeta();
-            if (itemMeta != null) {
-                itemMeta.write(itemNBT);
-            }
-        }
-        // End custom meta
-
-        // Start ownership
-        {
-            final Data data = itemStack.getData();
-            if (data != null && !data.isEmpty()) {
-                final UUID identifier = itemStack.getIdentifier();
-                itemNBT.setString(ItemStack.OWNERSHIP_DATA_KEY, identifier.toString());
-            }
-        }
-        // End ownership
-
-        //CanDestroy
-        {
-            Set<String> canDestroy = itemStack.getCanDestroy();
-            if (canDestroy.size() > 0) {
-                NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
-                canDestroy.forEach(x -> list.add(new NBTString(x)));
-                itemNBT.set("CanDestroy", list);
-            }
-        }
-
-        //CanDestroy
-        {
-            Set<String> canPlaceOn = itemStack.getCanPlaceOn();
-            if (canPlaceOn.size() > 0) {
-                NBTList<NBTString> list = new NBTList<>(NBTTypes.TAG_String);
-                canPlaceOn.forEach(x -> list.add(new NBTString(x)));
-                itemNBT.set("CanPlaceOn", list);
-            }
-        }
-    }
-
-    /**
-     * Converts an object into its {@link NBT} equivalent.
-     * <p>
-     * If {@code type} is not a primitive type or primitive array and {@code supportDataType} is true,
-     * the data will be encoded with the appropriate {@link DataType} into a byte array.
-     *
-     * @param value           the value to convert
-     * @param type            the type of the value, used to know which {@link DataType} to use if {@code value} is not a primitive type
-     * @param supportDataType true to allow using a {@link DataType} to encode {@code value} into a byte array if not a primitive type
-     * @return the converted value, null if {@code type} is not a primitive type and {@code supportDataType} is false
-     */
-    @Nullable
-    public static NBT toNBT(@NotNull Object value, @NotNull Class type, boolean supportDataType) {
-        type = PrimitiveConversion.getObjectClass(type);
-        if (type.equals(Boolean.class)) {
-            // No boolean type in NBT
-            return new NBTByte((byte) (((boolean) value) ? 1 : 0));
-        } else if (type.equals(Byte.class)) {
-            return new NBTByte((byte) value);
-        } else if (type.equals(Character.class)) {
-            // No char type in NBT
-            return new NBTShort((short) value);
-        } else if (type.equals(Short.class)) {
-            return new NBTShort((short) value);
-        } else if (type.equals(Integer.class)) {
-            return new NBTInt((int) value);
-        } else if (type.equals(Long.class)) {
-            return new NBTLong((long) value);
-        } else if (type.equals(Float.class)) {
-            return new NBTFloat((float) value);
-        } else if (type.equals(Double.class)) {
-            return new NBTDouble((double) value);
-        } else if (type.equals(String.class)) {
-            return new NBTString((String) value);
-        } else if (type.equals(Byte[].class)) {
-            return new NBTByteArray((byte[]) value);
-        } else if (type.equals(Integer[].class)) {
-            return new NBTIntArray((int[]) value);
-        } else if (type.equals(Long[].class)) {
-            return new NBTLongArray((long[]) value);
-        } else {
-            if (supportDataType) {
-                // Custom NBT type, try to encode using the data manager
-                DataType dataType = MinecraftServer.getDataManager().getDataType(type);
-                Check.notNull(dataType, "The type '" + type + "' is not registered in DataManager and not a primitive type.");
-
-                BinaryWriter writer = new BinaryWriter();
-                dataType.encode(writer, value);
-
-                final byte[] encodedValue = writer.toByteArray();
-
-                return new NBTByteArray(encodedValue);
-            } else {
-                return null;
-            }
-        }
-    }
-
-    /**
-     * Converts a nbt object to its raw value.
-     * <p>
-     * Currently support number, string, byte/int/long array.
-     *
-     * @param nbt the nbt tag to convert
-     * @return the value representation of a tag
-     * @throws UnsupportedOperationException if the tag type is not supported
-     */
-    @NotNull
-    public static Object fromNBT(@NotNull NBT nbt) {
-        if (nbt instanceof NBTNumber) {
-            return ((NBTNumber) nbt).getValue();
-        } else if (nbt instanceof NBTString) {
-            return ((NBTString) nbt).getValue();
-        } else if (nbt instanceof NBTByteArray) {
-            return ((NBTByteArray) nbt).getValue();
-        } else if (nbt instanceof NBTIntArray) {
-            return ((NBTIntArray) nbt).getValue();
-        } else if (nbt instanceof NBTLongArray) {
-            return ((NBTLongArray) nbt).getValue();
-        }
-
-        throw new UnsupportedOperationException("NBT type " + nbt.getClass() + " is not handled properly.");
-    }
-
     @FunctionalInterface
     public interface EnchantmentSetter {
         void applyEnchantment(Enchantment name, short level);

src/main/java/net/minestom/server/utils/binary/BinaryWriter.java

@@ -9,7 +9,6 @@ import net.minestom.server.adventure.AdventureSerializer;
 import net.minestom.server.chat.JsonMessage;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.utils.BlockPosition;
-import net.minestom.server.utils.NBTUtils;
 import net.minestom.server.utils.SerializerUtils;
 import net.minestom.server.utils.Utils;
 import org.jetbrains.annotations.NotNull;
@@ -264,7 +263,14 @@ public class BinaryWriter extends OutputStream {
     }
 
     public void writeItemStack(@NotNull ItemStack itemStack) {
-        NBTUtils.writeItemStack(this, itemStack);
+        if (itemStack.isAir()) {
+            writeBoolean(false);
+        } else {
+            writeBoolean(true);
+            writeVarInt(itemStack.getMaterial().getId());
+            writeByte((byte) itemStack.getAmount());
+            write(itemStack.getMeta());
+        }
     }
 
     public void writeNBT(@NotNull String name, @NotNull NBT tag) {

src/main/java/net/minestom/server/utils/ownership/OwnershipHandler.java

@@ -1,59 +0,0 @@
-package net.minestom.server.utils.ownership;
-
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.UUID;
-import java.util.concurrent.ConcurrentHashMap;
-
-/**
- * Convenient class to keep trace of objects linked to an {@link UUID}.
- *
- * @param <T> the owned object type
- */
-public class OwnershipHandler<T> {
-
-    // identifier = the object having an ownership
-    private ConcurrentHashMap<UUID, T> ownershipDataMap = new ConcurrentHashMap<>();
-
-    /**
-     * Generates a new unique identifier.
-     * <p>
-     * Does call {@link UUID#randomUUID()} internally.
-     *
-     * @return a new generated identifier
-     */
-    public UUID generateIdentifier() {
-        return UUID.randomUUID();
-    }
-
-    /**
-     * Retrieves the owned object based on its identifier.
-     *
-     * @param identifier the object identifier
-     * @return the own object, null if not found
-     */
-    @Nullable
-    public T getOwnObject(@NotNull UUID identifier) {
-        return ownershipDataMap.get(identifier);
-    }
-
-    /**
-     * Saves, replace or remove the own object of an identifier.
-     *
-     * @param identifier the identifier of the object
-     * @param value      the value of the object, can override the previous value, null means removing the identifier
-     */
-    public void saveOwnObject(@NotNull UUID identifier, @Nullable T value) {
-        if (value != null) {
-            this.ownershipDataMap.put(identifier, value);
-        } else {
-            clearCache(identifier);
-        }
-    }
-
-    public void clearCache(@NotNull UUID identifier) {
-        this.ownershipDataMap.remove(identifier);
-    }
-
-}

src/main/java/net/minestom/server/world/biomes/BiomeParticles.java

@@ -100,7 +100,7 @@ public class BiomeParticles {
         @Override
         public NBTCompound toNbt() {
             //todo test count might be wrong type
-            NBTCompound nbtCompound = item.toNBT();
+            NBTCompound nbtCompound = item.getMeta().toNBT();
             nbtCompound.setString("type", type);
             return nbtCompound;
         }

src/test/java/demo/Main.java

@@ -47,6 +47,7 @@ public class Main {
         commandManager.register(new EchoCommand());
         commandManager.register(new SummonCommand());
         commandManager.register(new RemoveCommand());
+        commandManager.register(new GiveCommand());
 
         commandManager.setUnknownCommandCallback((sender, command) -> sender.sendMessage(Component.text("Unknown command", NamedTextColor.RED)));
 

src/test/java/demo/PlayerInit.java

@@ -1,6 +1,5 @@
 package demo;
 
-import com.google.common.util.concurrent.AtomicDouble;
 import demo.generator.ChunkGeneratorDemo;
 import demo.generator.NoiseTestGenerator;
 import net.kyori.adventure.text.Component;
@@ -27,18 +26,20 @@ import net.minestom.server.inventory.Inventory;
 import net.minestom.server.inventory.InventoryType;
 import net.minestom.server.inventory.PlayerInventory;
 import net.minestom.server.item.ItemStack;
+import net.minestom.server.item.ItemTag;
 import net.minestom.server.item.Material;
+import net.minestom.server.item.metadata.CompassMeta;
 import net.minestom.server.monitoring.BenchmarkManager;
 import net.minestom.server.network.ConnectionManager;
 import net.minestom.server.ping.ResponseDataConsumer;
-import net.minestom.server.utils.MathUtils;
 import net.minestom.server.utils.Position;
 import net.minestom.server.utils.Vector;
-import net.minestom.server.utils.inventory.PlayerInventoryUtils;
 import net.minestom.server.utils.time.TimeUnit;
 import net.minestom.server.world.DimensionType;
 
 import java.util.Collection;
+import java.util.Collections;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.ThreadLocalRandom;
 
@@ -57,24 +58,40 @@ public class PlayerInit {
         instanceContainer.enableAutoChunkLoad(true);
         instanceContainer.setChunkGenerator(chunkGeneratorDemo);
 
-        inventory = new Inventory(InventoryType.CHEST_1_ROW, "Test inventory");
+        inventory = new Inventory(InventoryType.CHEST_1_ROW, Component.text("Test inventory"));
         /*inventory.addInventoryCondition((p, slot, clickType, inventoryConditionResult) -> {
             p.sendMessage("click type inventory: " + clickType);
             System.out.println("slot inv: " + slot)0;
             inventoryConditionResult.setCancel(slot == 3);
         });*/
-        //inventory.setItemStack(3, new ItemStack(Material.DIAMOND, (byte) 34));
+        inventory.setItemStack(3, ItemStack.of(Material.DIAMOND, 34));
-    }
 
-    private static final AtomicDouble LAST_TICK_TIME = new AtomicDouble();
+        {
+            CompassMeta compassMeta = new CompassMeta.Builder()
+                    .lodestonePosition(new Position(0, 0, 0))
+                    .build();
+
+            ItemStack itemStack = ItemStack.builder(Material.COMPASS)
+                    .meta(CompassMeta.class, builder -> {
+                        builder.lodestonePosition(new Position(0, 0, 0));
+                        builder.set(ItemTag.Integer("int"), 25);
+                    })
+                    .build();
+
+            itemStack = itemStack.with(itemBuilder -> itemBuilder
+                    .amount(10)
+                    .meta(CompassMeta.class, builder -> {
+                        builder.lodestonePosition(new Position(5, 0, 0));
+                    })
+                    .lore(Component.text("Lore")));
+        }
+
+    }
 
     public static void init() {
         ConnectionManager connectionManager = MinecraftServer.getConnectionManager();
         BenchmarkManager benchmarkManager = MinecraftServer.getBenchmarkManager();
 
-        MinecraftServer.getUpdateManager().addTickMonitor(tickMonitor ->
-                LAST_TICK_TIME.set(tickMonitor.getTickTime()));
-
         MinecraftServer.getSchedulerManager().buildTask(() -> {
 
             Collection<Player> players = connectionManager.getOnlinePlayers();
@@ -85,9 +102,7 @@ public class PlayerInit {
             long ramUsage = benchmarkManager.getUsedMemory();
             ramUsage /= 1e6; // bytes to MB
 
-            final Component header = Component.text("RAM USAGE: " + ramUsage + " MB")
+            final Component header = Component.text("RAM USAGE: " + ramUsage + " MB");
-                    .append(Component.newline())
-                    .append(Component.text("TICK TIME: " + MathUtils.round(LAST_TICK_TIME.get(), 2) + "ms"));
             final Component footer = benchmarkManager.getCpuMonitoringMessage();
             Audiences.players().sendPlayerListHeaderAndFooter(header, footer);
 
@@ -189,6 +204,7 @@ public class PlayerInit {
 
         globalEventHandler.addEventCallback(PlayerLoginEvent.class, event -> {
             final Player player = event.getPlayer();
+            player.sendMessage("test");
 
             event.setSpawningInstance(instanceContainer);
             int x = Math.abs(ThreadLocalRandom.current().nextInt()) % 1000 - 250;
@@ -210,19 +226,31 @@ public class PlayerInit {
             player.setPermissionLevel(4);
 
             PlayerInventory inventory = player.getInventory();
-            ItemStack itemStack = new ItemStack(Material.STONE, (byte) 64);
+            ItemStack itemStack = ItemStack.builder(Material.STONE)
+                    .amount(64)
+                    .meta(itemMetaBuilder ->
+                            itemMetaBuilder.canPlaceOn(Set.of(Block.STONE))
+                                    .canDestroy(Set.of(Block.DIAMOND_ORE)))
+                    .build();
+
+            System.out.println(itemStack.getMeta().toSNBT());
+
+            //itemStack = itemStack.withStore(storeBuilder -> storeBuilder.set("key2", 25, Integer::sum));
+
             inventory.addItemStack(itemStack);
 
             {
-                ItemStack item = new ItemStack(Material.DIAMOND_CHESTPLATE, (byte) 1);
+                ItemStack item = ItemStack.builder(Material.DIAMOND_CHESTPLATE)
-                inventory.setChestplate(item);
+                        .displayName(Component.text("test"))
-                item.setDisplayName(ColoredText.of("test"));
+                        .lore(Component.text("lore"))
+                        .build();
 
-                inventory.refreshSlot((short) PlayerInventoryUtils.CHESTPLATE_SLOT);
+                //inventory.setChestplate(item);
 
+                inventory.setChestplate(item.with(itemStackBuilder -> {
+                    itemStackBuilder.lore(Collections.emptyList());
+                }));
             }
-
-            //player.getInventory().addItemStack(new ItemStack(Material.STONE, (byte) 32));
         });
 
         globalEventHandler.addEventCallback(PlayerBlockBreakEvent.class, event -> {

src/test/java/demo/commands/GiveCommand.java

@@ -0,0 +1,58 @@
+package demo.commands;
+
+import net.kyori.adventure.text.Component;
+import net.minestom.server.command.builder.Command;
+import net.minestom.server.entity.Entity;
+import net.minestom.server.entity.Player;
+import net.minestom.server.inventory.PlayerInventory;
+import net.minestom.server.inventory.TransactionOption;
+import net.minestom.server.item.ItemStack;
+import net.minestom.server.utils.entity.EntityFinder;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static net.minestom.server.command.builder.arguments.ArgumentType.Integer;
+import static net.minestom.server.command.builder.arguments.ArgumentType.*;
+
+public class GiveCommand extends Command {
+    public GiveCommand() {
+        super("give");
+
+        setDefaultExecutor((sender, context) ->
+                sender.sendMessage(Component.text("Usage: /give <target> <item> [<count>]")));
+
+        addSyntax((sender, context) -> {
+            final EntityFinder entityFinder = context.get("target");
+            int count = context.get("count");
+            count = Math.min(count, PlayerInventory.INVENTORY_SIZE * 64);
+            ItemStack itemStack = context.get("item");
+
+            List<ItemStack> itemStacks;
+            if (count <= 64) {
+                itemStack = itemStack.withAmount(count);
+                itemStacks = Collections.singletonList(itemStack);
+            } else {
+                itemStacks = new ArrayList<>();
+                while (count > 64) {
+                    itemStacks.add(itemStack.withAmount(64));
+                    count -= 64;
+                }
+                itemStacks.add(itemStack.withAmount(count));
+            }
+
+            final List<Entity> targets = entityFinder.find(sender);
+            for (Entity target : targets) {
+                if (target instanceof Player) {
+                    Player player = (Player) target;
+                    player.getInventory().addItemStacks(itemStacks, TransactionOption.ALL);
+                }
+            }
+
+            sender.sendMessage(Component.text("Items have been given successfully!"));
+
+        }, Entity("target").onlyPlayers(true), ItemStack("item"), Integer("count").setDefaultValue(() -> 1));
+
+    }
+}

src/test/java/readwritepackets/ReadWritePackets.java

@@ -47,13 +47,13 @@ public class ReadWritePackets {
     private <T extends Readable & Writeable> Collection<DynamicTest> checkImplementationPresence(Class<T> packetClass) throws IOException {
         ClassPath cp = ClassPath.from(ClassLoader.getSystemClassLoader());
         List<DynamicTest> allTests = new LinkedList<>();
-        for(ClassPath.ClassInfo classInfo : cp.getAllClasses()) {
+        for (ClassPath.ClassInfo classInfo : cp.getAllClasses()) {
-            if(!classInfo.getPackageName().startsWith("net.minestom.server.network.packet"))
+            if (!classInfo.getPackageName().startsWith("net.minestom.server.network.packet"))
                 continue;
             try {
                 Class<?> clazz = classInfo.load();
-                if(packetClass.isAssignableFrom(clazz) && !clazz.isInterface() && ((clazz.getModifiers() & Modifier.ABSTRACT) != Modifier.ABSTRACT)) {
+                if (packetClass.isAssignableFrom(clazz) && !clazz.isInterface() && ((clazz.getModifiers() & Modifier.ABSTRACT) != Modifier.ABSTRACT)) {
-                    allTests.add(DynamicTest.dynamicTest("WriteThenRead "+clazz.getSimpleName(), () -> {
+                    allTests.add(DynamicTest.dynamicTest("WriteThenRead " + clazz.getSimpleName(), () -> {
                         // required for managers to be loaded
                         MinecraftServer.init();
 
@@ -63,14 +63,13 @@ public class ReadWritePackets {
                         T packet;
 
                         // exceptions
-                        if(clazz.getSimpleName().equals("EntityEquipmentPacket")) {
+                        if (clazz.getSimpleName().equals("EntityEquipmentPacket")) {
                             // requires at least one slot and one item
                             EntityEquipmentPacket p = new EntityEquipmentPacket();
-                            p.itemStacks = new ItemStack[] { ItemStack.getAirItem() };
+                            p.itemStacks = new ItemStack[]{ItemStack.AIR};
-                            p.slots = new EntityEquipmentPacket.Slot[] { EntityEquipmentPacket.Slot.MAIN_HAND };
+                            p.slots = new EntityEquipmentPacket.Slot[]{EntityEquipmentPacket.Slot.MAIN_HAND};
                             packet = (T) p;
-                        }
+                        } else {
-                        else {
                             packet = (T) constructor.newInstance();
                         }