Added Entity#isAutoViewable & making Viewable#addViewer and Viewable#removeViewer return boolean

src/main/java/fr/themode/demo/PlayerInit.java

@@ -8,6 +8,7 @@ import net.minestom.server.benchmark.BenchmarkManager;
 import net.minestom.server.benchmark.ThreadResult;
 import net.minestom.server.entity.*;
 import net.minestom.server.entity.damage.DamageType;
+import net.minestom.server.entity.type.EntityBoat;
 import net.minestom.server.event.entity.EntityAttackEvent;
 import net.minestom.server.event.item.ItemDropEvent;
 import net.minestom.server.event.item.ItemUpdateStateEvent;
@@ -19,11 +20,12 @@ import net.minestom.server.instance.InstanceContainer;
 import net.minestom.server.instance.block.Block;
 import net.minestom.server.inventory.Inventory;
 import net.minestom.server.inventory.InventoryType;
+import net.minestom.server.item.Enchantment;
+import net.minestom.server.item.ItemFlag;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.item.Material;
 import net.minestom.server.network.ConnectionManager;
 import net.minestom.server.ping.ResponseDataConsumer;
-import net.minestom.server.scoreboard.Sidebar;
 import net.minestom.server.timer.TaskRunnable;
 import net.minestom.server.utils.MathUtils;
 import net.minestom.server.utils.Position;
@@ -40,6 +42,8 @@ public class PlayerInit {
     private static volatile InstanceContainer instanceContainer;
     private static volatile InstanceContainer netherTest;
 
+    private static volatile Inventory inventory;
+
     static {
         //StorageFolder storageFolder = MinecraftServer.getStorageManager().getFolder("chunk_data");
         ChunkGeneratorDemo chunkGeneratorDemo = new ChunkGeneratorDemo();
@@ -61,6 +65,15 @@ public class PlayerInit {
                 instanceContainer.loadChunk(x, z);
                 netherTest.loadChunk(x, z);
             }
+
+
+        inventory = new Inventory(InventoryType.CHEST_1_ROW, "Test inventory");
+        inventory.addInventoryCondition((p, slot, clickType, inventoryConditionResult) -> {
+            p.sendMessage("click type inventory: " + clickType);
+            System.out.println("slot inv: " + slot);
+            inventoryConditionResult.setCancel(false);
+        });
+        inventory.setItemStack(0, new ItemStack(Material.DIAMOND, (byte) 34));
     }
 
     public static void init() {
@@ -157,9 +170,9 @@ public class PlayerInit {
             player.addEventCallback(ItemDropEvent.class, event -> {
                 ItemStack droppedItem = event.getItemStack();
 
-                ItemEntity itemEntity = new ItemEntity(droppedItem);
+                Position position = player.getPosition().clone().add(0, 1.5f, 0);
-                itemEntity.setPickupDelay(500);
+                ItemEntity itemEntity = new ItemEntity(droppedItem, position);
-                itemEntity.refreshPosition(player.getPosition().clone().add(0, 1.5f, 0));
+                itemEntity.setPickupDelay(500, TimeUnit.MILLISECOND);
                 itemEntity.setInstance(player.getInstance());
                 Vector velocity = player.getPosition().clone().getDirection().multiply(6);
                 itemEntity.setVelocity(velocity);
@@ -179,38 +192,36 @@ public class PlayerInit {
                     System.out.println("slot player: " + slot);
                 });
 
-                Sidebar scoreboard = new Sidebar("Scoreboard Title");
+                /*Sidebar scoreboard = new Sidebar("Scoreboard Title");
                 for (int i = 0; i < 15; i++) {
                     scoreboard.createLine(new Sidebar.ScoreboardLine("id" + i, "Hey guys " + i, i));
                 }
                 scoreboard.addViewer(player);
                 scoreboard.updateLineContent("id3", "I HAVE BEEN UPDATED");
 
-                scoreboard.setTitle("test");
+                scoreboard.setTitle("test");*/
             });
 
             player.addEventCallback(PlayerSpawnEvent.class, event -> {
                 player.setGameMode(GameMode.SURVIVAL);
-                player.teleport(new Position(0, 75, 0));
+                player.teleport(new Position(0, 70, 0));
 
-                ItemStack item = new ItemStack(Material.STONE, (byte) 43);
+                ItemStack item = new ItemStack(Material.STONE_SWORD, (byte) 1);
                 item.setDisplayName("Item name");
                 item.getLore().add("a lore line");
-                //item.setEnchantment(Enchantment.SHARPNESS, 2);
+                item.addItemFlags(ItemFlag.HIDE_ATTRIBUTES);
+                item.setEnchantment(Enchantment.SHARPNESS, (short) 2);
                 player.getInventory().addItemStack(item);
 
-                Inventory inventory = new Inventory(InventoryType.CHEST_1_ROW, "Test inventory");
-                inventory.addInventoryCondition((p, slot, clickType, inventoryConditionResult) -> {
-                    player.sendMessage("click type inventory: " + clickType);
-                    System.out.println("slot inv: " + slot);
-                    inventoryConditionResult.setCancel(false);
-                });
-                inventory.setItemStack(0, item.clone());
-
                 player.openInventory(inventory);
 
                 player.getInventory().addItemStack(new ItemStack(Material.STONE, (byte) 100));
-                player.getInventory().addItemStack(new ItemStack(Material.DIAMOND_CHESTPLATE, (byte) 1));
+
+                EntityBoat entityBoat = new EntityBoat(player.getPosition());
+                entityBoat.setInstance(player.getInstance());
+                //entityBoat.addPassenger(player);
+
+                //player.getInventory().addItemStack(new ItemStack(Material.DIAMOND_CHESTPLATE, (byte) 1));
 
             /*TeamManager teamManager = Main.getTeamManager();
             Team team = teamManager.createTeam(getUsername());

src/main/java/fr/themode/demo/entity/ChickenCreature.java

@@ -14,6 +14,9 @@ public class ChickenCreature extends EntityCreature {
 
     public ChickenCreature(Position defaultPosition) {
         super(EntityType.SKELETON, defaultPosition);
+
+        setAutoViewable(true);
+
         setBoundingBox(0.4f, 0.7f, 0.4f);
         setHelmet(new ItemStack(Material.DIAMOND_HELMET, (byte) 1));
     }

src/main/java/net/minestom/server/Viewable.java

@@ -9,9 +9,17 @@ import java.util.Set;
 
 public interface Viewable {
 
-    void addViewer(Player player);
+    /**
+     * @param player the viewer to add
+     * @return true if the player has been added, false otherwise (could be because he is already a viewer)
+     */
+    boolean addViewer(Player player);
 
-    void removeViewer(Player player);
+    /**
+     * @param player the viewer to remove
+     * @return true if the player has been removed, false otherwise (could be because he was not a viewer)
+     */
+    boolean removeViewer(Player player);
 
     Set<Player> getViewers();
 

src/main/java/net/minestom/server/bossbar/BossBar.java

@@ -27,17 +27,19 @@ public class BossBar implements Viewable {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
         player.refreshAddBossbar(this);
         addToPlayer(player);
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        this.viewers.remove(player);
+        boolean result = this.viewers.remove(player);
         player.refreshRemoveBossbar(this);
         removeToPlayer(player);
+        return result;
     }
 
     @Override

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

@@ -61,6 +61,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
     protected float gravityDragPerTick;
     protected float eyeHeight;
 
+    private boolean autoViewable;
     private Set<Player> viewers = new CopyOnWriteArraySet<>();
     private Data data;
     private Set<Entity> passengers = new CopyOnWriteArraySet<>();
@@ -110,6 +111,8 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
 
         setBoundingBox(0, 0, 0);
 
+        setAutoViewable(true);
+
         entityById.put(id, this);
         setVelocityUpdatePeriod(5);
     }
@@ -204,27 +207,54 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
         teleport(position, null);
     }
 
+    /**
+     * When set to true, the entity will automatically get new viewers when they come too close
+     * This can be use to complete control over which player can see it, without having to deal with
+     * raw packets
+     * <p>
+     * True by default for all entities
+     * When set to false, it is important to mention that the players will not be removed automatically from its viewers
+     * list, you would have to do that manually when being too far
+     *
+     * @return true if the entity is automatically viewable for close players, false otherwise
+     */
+    public boolean isAutoViewable() {
+        return autoViewable;
+    }
+
+    /**
+     * @param autoViewable should the entity be automatically viewable for close players
+     */
+    public void setAutoViewable(boolean autoViewable) {
+        this.autoViewable = autoViewable;
+    }
+
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
         player.viewableEntities.add(this);
         PlayerConnection playerConnection = player.getPlayerConnection();
         playerConnection.sendPacket(getVelocityPacket());
         playerConnection.sendPacket(getPassengersPacket());
         playerConnection.sendPacket(getMetadataPacket());
+
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
+        boolean result;
         synchronized (viewers) {
-            if (!viewers.contains(player))
+            result = viewers.remove(player);
-                return;
+            if (!result)
-            this.viewers.remove(player);
+                return false;
+
             DestroyEntitiesPacket destroyEntitiesPacket = new DestroyEntitiesPacket();
             destroyEntitiesPacket.entityIds = new int[]{getEntityId()};
             player.getPlayerConnection().sendPacket(destroyEntitiesPacket);
         }
         player.viewableEntities.remove(this);
+        return result;
     }
 
     @Override
@@ -571,7 +601,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
                     instance.removeEntityFromChunk(this, lastChunk);
                     instance.addEntityToChunk(this, newChunk);
                 }
-                updateView(this, lastChunk, newChunk);
+                updateView(lastChunk, newChunk);
             }
         }
     }
@@ -580,16 +610,16 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
         refreshPosition(position.getX(), position.getY(), position.getZ());
     }
 
-    private void updateView(Entity entity, Chunk lastChunk, Chunk newChunk) {
+    private void updateView(Chunk lastChunk, Chunk newChunk) {
-        if (entity instanceof Player)
+        boolean isPlayer = this instanceof Player;
-            ((Player) entity).onChunkChange(lastChunk, newChunk); // Refresh loaded chunk
+
+        if (isPlayer)
+            ((Player) this).onChunkChange(lastChunk, newChunk); // Refresh loaded chunk
 
         // Refresh entity viewable list
         long[] lastVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * lastChunk.getChunkX(), 0, 16 * lastChunk.getChunkZ()), MinecraftServer.ENTITY_VIEW_DISTANCE);
         long[] updatedVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * newChunk.getChunkX(), 0, 16 * newChunk.getChunkZ()), MinecraftServer.ENTITY_VIEW_DISTANCE);
 
-        boolean isPlayer = entity instanceof Player;
-
         int[] oldChunksEntity = ArrayUtils.getDifferencesBetweenArray(lastVisibleChunksEntity, updatedVisibleChunksEntity);
         for (int index : oldChunksEntity) {
             int[] chunkPos = ChunkUtils.getChunkCoord(lastVisibleChunksEntity[index]);
@@ -599,12 +629,13 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
             instance.getChunkEntities(chunk).forEach(ent -> {
                 if (ent instanceof Player) {
                     Player player = (Player) ent;
-                    removeViewer(player);
+                    if (isAutoViewable())
+                        removeViewer(player);
                     if (isPlayer) {
-                        player.removeViewer((Player) entity);
+                        player.removeViewer((Player) this);
                     }
                 } else if (isPlayer) {
-                    ent.removeViewer((Player) entity);
+                    ent.removeViewer((Player) this);
                 }
             });
         }
@@ -618,12 +649,13 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
             instance.getChunkEntities(chunk).forEach(ent -> {
                 if (ent instanceof Player) {
                     Player player = (Player) ent;
-                    addViewer(player);
+                    if (isAutoViewable())
-                    if (entity instanceof Player) {
+                        addViewer(player);
-                        player.addViewer((Player) entity);
+                    if (this instanceof Player) {
+                        player.addViewer((Player) this);
                     }
                 } else if (isPlayer) {
-                    ent.addViewer((Player) entity);
+                    ent.addViewer((Player) this);
                 }
             });
         }

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

@@ -133,8 +133,8 @@ public abstract class EntityCreature extends LivingEntity {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        super.addViewer(player);
+        boolean result = super.addViewer(player);
         PlayerConnection playerConnection = player.getPlayerConnection();
 
         EntityPacket entityPacket = new EntityPacket();
@@ -150,6 +150,7 @@ public abstract class EntityCreature extends LivingEntity {
         playerConnection.sendPacket(entityPacket);
         playerConnection.sendPacket(spawnLivingEntityPacket);
         playerConnection.sendPacket(getMetadataPacket());
+        return result;
     }
 
     @Override

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

@@ -25,7 +25,7 @@ public class ExperienceOrb extends Entity {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
         PlayerConnection playerConnection = player.getPlayerConnection();
 
         SpawnExperienceOrbPacket experienceOrbPacket = new SpawnExperienceOrbPacket();
@@ -33,7 +33,7 @@ public class ExperienceOrb extends Entity {
         experienceOrbPacket.position = getPosition();
         experienceOrbPacket.expCount = experienceCount;
         playerConnection.sendPacket(experienceOrbPacket);
-        super.addViewer(player); // Add player to viewers list and send velocity packet
+        return super.addViewer(player); // Add player to viewers list and send velocity packet
     }
 
     public short getExperienceCount() {

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

@@ -6,6 +6,7 @@ import net.minestom.server.item.ItemStack;
 import net.minestom.server.item.StackingRule;
 import net.minestom.server.network.packet.PacketWriter;
 import net.minestom.server.utils.Position;
+import net.minestom.server.utils.time.TimeUnit;
 
 import java.util.Set;
 import java.util.function.Consumer;
@@ -83,11 +84,6 @@ public class ItemEntity extends ObjectEntity {
         this.spawnTime = System.currentTimeMillis();
     }
 
-    @Override
-    public void addViewer(Player player) {
-        super.addViewer(player);
-    }
-
     @Override
     public Consumer<PacketWriter> getMetadataConsumer() {
         return packet -> {
@@ -118,7 +114,7 @@ public class ItemEntity extends ObjectEntity {
 
     public void setItemStack(ItemStack itemStack) {
         this.itemStack = itemStack;
-        sendMetadataIndex(7); // Refresh itemstack for viewers
+        sendMetadataIndex(7); // Refresh the ItemStack for viewers
     }
 
     public boolean isPickable() {
@@ -141,8 +137,8 @@ public class ItemEntity extends ObjectEntity {
         return pickupDelay;
     }
 
-    public void setPickupDelay(long pickupDelay) {
+    public void setPickupDelay(long delay, TimeUnit timeUnit) {
-        this.pickupDelay = pickupDelay;
+        this.pickupDelay = timeUnit.toMilliseconds(delay);
     }
 
     public long getSpawnTime() {

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

@@ -81,6 +81,11 @@ public abstract class LivingEntity extends Entity implements EquipmentHandler {
             BoundingBox livingBoundingBox = expandedBoundingBox;
             for (Entity entity : entities) {
                 if (entity instanceof ItemEntity) {
+
+                    // Do not pickup if not visible
+                    if (this instanceof Player && !entity.isViewer((Player) this))
+                        continue;
+
                     ItemEntity itemEntity = (ItemEntity) entity;
                     if (!itemEntity.isPickable())
                         continue;
@@ -135,11 +140,12 @@ public abstract class LivingEntity extends Entity implements EquipmentHandler {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        super.addViewer(player);
+        boolean result = super.addViewer(player);
 
         // Equipments synchronization
         syncEquipments();
+        return result;
     }
 
     /**

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

@@ -14,7 +14,7 @@ public abstract class ObjectEntity extends Entity {
     public abstract int getObjectData();
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
         PlayerConnection playerConnection = player.getPlayerConnection();
 
         SpawnEntityPacket spawnEntityPacket = new SpawnEntityPacket();
@@ -25,12 +25,12 @@ public abstract class ObjectEntity extends Entity {
         spawnEntityPacket.data = getObjectData();
         playerConnection.sendPacket(spawnEntityPacket);
         playerConnection.sendPacket(getMetadataPacket());
-        super.addViewer(player); // Add player to viewers list and send velocity packet
+        return super.addViewer(player); // Add player to viewers list and send velocity packet
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        super.removeViewer(player);
+        return super.removeViewer(player);
     }
 
 }

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

@@ -333,10 +333,11 @@ public class Player extends LivingEntity {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
         if (player == this)
-            return;
+            return false;
-        super.addViewer(player);
+
+        boolean result = super.addViewer(player);
         PlayerConnection viewerConnection = player.getPlayerConnection();
         String property = "eyJ0aW1lc3RhbXAiOjE1NjU0ODMwODQwOTYsInByb2ZpbGVJZCI6ImFiNzBlY2I0MjM0NjRjMTRhNTJkN2EwOTE1MDdjMjRlIiwicHJvZmlsZU5hbWUiOiJUaGVNb2RlOTExIiwidGV4dHVyZXMiOnsiU0tJTiI6eyJ1cmwiOiJodHRwOi8vdGV4dHVyZXMubWluZWNyYWZ0Lm5ldC90ZXh0dXJlL2RkOTE2NzJiNTE0MmJhN2Y3MjA2ZTRjN2IwOTBkNzhlM2Y1ZDc2NDdiNWFmZDIyNjFhZDk4OGM0MWI2ZjcwYTEifX19";
         SpawnPlayerPacket spawnPlayerPacket = new SpawnPlayerPacket();
@@ -356,13 +357,15 @@ public class Player extends LivingEntity {
         // Team
         if (team != null)
             viewerConnection.sendPacket(team.getTeamsCreationPacket());
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
         if (player == this)
-            return;
+            return false;
-        super.removeViewer(player);
+
+        boolean result = super.removeViewer(player);
         PlayerConnection viewerConnection = player.getPlayerConnection();
         PlayerInfoPacket playerInfoPacket = new PlayerInfoPacket(PlayerInfoPacket.Action.REMOVE_PLAYER);
         playerInfoPacket.playerInfos.add(new PlayerInfoPacket.RemovePlayer(getUuid()));
@@ -371,6 +374,7 @@ public class Player extends LivingEntity {
         // Team
         if (team != null && team.getPlayers().size() == 1) // If team only contains "this" player
             viewerConnection.sendPacket(team.createTeamDestructionPacket());
+        return result;
     }
 
     @Override

src/main/java/net/minestom/server/instance/Chunk.java

@@ -374,20 +374,22 @@ public class Chunk implements Viewable {
 
     // UNSAFE
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
 
         PlayerChunkLoadEvent playerChunkLoadEvent = new PlayerChunkLoadEvent(player, chunkX, chunkZ);
         player.callEvent(PlayerChunkLoadEvent.class, playerChunkLoadEvent);
+        return result;
     }
 
     // UNSAFE
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        this.viewers.remove(player);
+        boolean result = this.viewers.remove(player);
 
         PlayerChunkUnloadEvent playerChunkUnloadEvent = new PlayerChunkUnloadEvent(player, chunkX, chunkZ);
         player.callEvent(PlayerChunkUnloadEvent.class, playerChunkUnloadEvent);
+        return result;
     }
 
     @Override

src/main/java/net/minestom/server/instance/Instance.java

@@ -315,7 +315,8 @@ public abstract class Instance implements BlockModifier, EventHandler, DataConta
                     }
 
                     if (ent instanceof Player) {
-                        entity.addViewer((Player) ent);
+                        if (entity.isAutoViewable())
+                            entity.addViewer((Player) ent);
                     }
                 });
             }
@@ -332,7 +333,10 @@ public abstract class Instance implements BlockModifier, EventHandler, DataConta
 
         RemoveEntityFromInstanceEvent event = new RemoveEntityFromInstanceEvent(this, entity);
         callCancellableEvent(RemoveEntityFromInstanceEvent.class, event, () -> {
-            entity.getViewers().forEach(p -> entity.removeViewer(p)); // Remove this entity from players viewable list and send delete entities packet
+            if (entity.isAutoViewable()) {
+                // Remove this entity from players viewable list and send delete entities packet
+                entity.getViewers().forEach(p -> entity.removeViewer(p));
+            }
 
             Chunk chunk = getChunkAt(entity.getPosition());
             removeEntityFromChunk(entity, chunk);

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

@@ -133,7 +133,7 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
     public void update(Player player) {
         if (!getViewers().contains(player))
             return;
-        
+
         PacketWriterUtils.writeAndSend(player, getWindowItemsPacket());
     }
 
@@ -143,17 +143,19 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
         WindowItemsPacket windowItemsPacket = getWindowItemsPacket();
         player.getPlayerConnection().sendPacket(windowItemsPacket);
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        this.viewers.remove(player);
+        boolean result = this.viewers.remove(player);
         this.cursorPlayersItem.remove(player);
         this.clickProcessor.clearCache(player);
+        return result;
     }
 
     public ItemStack getCursorItem(Player player) {

src/main/java/net/minestom/server/scoreboard/BelowNameScoreboard.java

@@ -53,15 +53,16 @@ public class BelowNameScoreboard implements Viewable {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
         PlayerConnection playerConnection = player.getPlayerConnection();
         playerConnection.sendPacket(scoreboardObjectivePacket);
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        this.viewers.remove(player);
+        return this.viewers.remove(player);
     }
 
     @Override

src/main/java/net/minestom/server/scoreboard/Sidebar.java

@@ -124,8 +124,8 @@ public class Sidebar implements Viewable {
     }
 
     @Override
-    public void addViewer(Player player) {
+    public boolean addViewer(Player player) {
-        this.viewers.add(player);
+        boolean result = this.viewers.add(player);
         PlayerConnection playerConnection = player.getPlayerConnection();
 
         ScoreboardObjectivePacket scoreboardObjectivePacket = new ScoreboardObjectivePacket();
@@ -145,11 +145,12 @@ public class Sidebar implements Viewable {
             playerConnection.sendPacket(line.sidebarTeam.getCreationPacket());
             playerConnection.sendPacket(line.getScoreCreationPacket(objectiveName));
         }
+        return result;
     }
 
     @Override
-    public void removeViewer(Player player) {
+    public boolean removeViewer(Player player) {
-        this.viewers.remove(player);
+        boolean result = this.viewers.remove(player);
         PlayerConnection playerConnection = player.getPlayerConnection();
         ScoreboardObjectivePacket scoreboardObjectivePacket = new ScoreboardObjectivePacket();
         scoreboardObjectivePacket.objectiveName = objectiveName;
@@ -160,6 +161,7 @@ public class Sidebar implements Viewable {
             playerConnection.sendPacket(line.getScoreDestructionPacket(objectiveName)); // Is it necessary?
             playerConnection.sendPacket(line.sidebarTeam.getDestructionPacket());
         }
+        return result;
     }
 
     @Override