Initial refactoring of the API

api/src/main/java/me/filoghost/holographicdisplays/api/Hologram.java

@@ -15,7 +15,9 @@ import org.bukkit.inventory.ItemStack;
 /**
  * An object made of various lines, that can be items or holograms.
  * Holographic lines appear as a nametag without any entity below.
- * To create one, please see {@link HologramsAPI#createHologram(org.bukkit.plugin.Plugin, Location)}.
+ * To create one, please see {@link HolographicDisplaysAPI#createHologram(Location)}.
+ * 
+ * @since 1
  */
 public interface Hologram {
     
@@ -24,6 +26,7 @@ public interface Hologram {
      * 
      * @param text the content of the line, can be null for an empty line
      * @return the new TextLine appended
+     * @since 1
      */
     TextLine appendTextLine(String text);
     
@@ -33,6 +36,7 @@ public interface Hologram {
      * 
      * @param itemStack the content of the line
      * @return the new ItemLine appended
+     * @since 1
      */
     ItemLine appendItemLine(ItemStack itemStack);
     
@@ -45,6 +49,7 @@ public interface Hologram {
      * @param text the content of the line, can be null for an empty line
      * @return the new TextLine inserted
      * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
      */
     TextLine insertTextLine(int index, String text);
     
@@ -57,6 +62,7 @@ public interface Hologram {
      * @param itemStack the content of the line
      * @return the new ItemLine inserted
      * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
      */
     ItemLine insertItemLine(int index, ItemStack itemStack);
     
@@ -67,6 +73,7 @@ public interface Hologram {
      * @param index the index of the line to retrieve.
      * @return the hologram line at the given index, can be an {@link ItemLine} or a {@link TextLine}.
      * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
      */
     HologramLine getLine(int index);
     
@@ -75,12 +82,15 @@ public interface Hologram {
      * 
      * @param index the index of the line, that should be between 0 and size() - 1.
      * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
      */
     void removeLine(int index);
     
     
     /**
      * Removes all the lines from this hologram.
+     * 
+     * @since 1
      */
     void clearLines();
 
@@ -89,6 +99,7 @@ public interface Hologram {
      * Checks the amount of lines of the hologram.
      * 
      * @return the amount of lines
+     * @since 1
      */
     int size();
     
@@ -97,6 +108,7 @@ public interface Hologram {
      * The physical height of the hologram, counting all the lines. Since: v2.1.4
      * 
      * @return the height of the hologram, counting all the lines and the gaps between them
+     * @since 1
      */
     double getHeight();
     
@@ -105,6 +117,7 @@ public interface Hologram {
      * Teleports a hologram to the given location.
      * 
      * @param location the new location
+     * @since 1
      */
     void teleport(Location location);
     
@@ -117,6 +130,7 @@ public interface Hologram {
      * @param x the X coordinate
      * @param y the Y coordinate
      * @param z the Z coordinate
+     * @since 1
      */
     void teleport(World world, double x, double y, double z);
     
@@ -124,6 +138,7 @@ public interface Hologram {
      * Returns the position of the hologram.
      * 
      * @return the Location of the hologram
+     * @since 1
      */
     Location getLocation();
     
@@ -131,6 +146,7 @@ public interface Hologram {
      * Returns the X coordinate.
      * 
      * @return the X coordinate of the hologram
+     * @since 1
      */
     double getX();
     
@@ -139,6 +155,7 @@ public interface Hologram {
      * Returns the Y coordinate.
      * 
      * @return the Y coordinate of the hologram
+     * @since 1
      */
     double getY();
     
@@ -147,6 +164,7 @@ public interface Hologram {
      * Returns the Z coordinate.
      * 
      * @return the Z coordinate of the hologram
+     * @since 1
      */
     double getZ();
     
@@ -155,6 +173,7 @@ public interface Hologram {
      * Returns the world.
      * 
      * @return the world of the hologram
+     * @since 1
      */
     World getWorld();
     
@@ -165,6 +184,7 @@ public interface Hologram {
      * Without the plugin, holograms will be always visible.
      * 
      * @return the VisibilityManager of this hologram
+     * @since 1
      */
     VisibilityManager getVisibilityManager();
     
@@ -173,6 +193,7 @@ public interface Hologram {
      * Returns when the hologram was created. Useful for removing old holograms.
      * 
      * @return the timestamp of when the hologram was created, in milliseconds
+     * @since 1
      */
     long getCreationTimestamp();
 
@@ -181,6 +202,7 @@ public interface Hologram {
      * This is false by default.
      * 
      * @return if the hologram allows placeholders
+     * @since 1
      */
     boolean isAllowPlaceholders();
 
@@ -189,6 +211,7 @@ public interface Hologram {
      * By default if will not track them.
      * 
      * @param allowPlaceholders if the hologram should track placeholders
+     * @since 1
      */
     void setAllowPlaceholders(boolean allowPlaceholders);
     
@@ -196,6 +219,8 @@ public interface Hologram {
      * Deletes this hologram. Editing or teleporting the hologram when deleted
      * will throw an exception. Lines will be automatically cleared.
      * You should remove all the references of the hologram after deletion.
+     * 
+     * @since 1
      */
     void delete();
     
@@ -204,6 +229,7 @@ public interface Hologram {
      * Checks if a hologram was deleted.
      * 
      * @return true if this hologram was deleted
+     * @since 1
      */
     boolean isDeleted();
     

api/src/main/java/me/filoghost/holographicdisplays/api/HologramsAPI.java

@@ -1,99 +0,0 @@
-/*
- * Copyright (C) filoghost and contributors
- *
- * SPDX-License-Identifier: GPL-3.0-or-later
- */
-package me.filoghost.holographicdisplays.api;
-
-import me.filoghost.holographicdisplays.api.internal.BackendAPI;
-import me.filoghost.holographicdisplays.api.placeholder.PlaceholderReplacer;
-import org.bukkit.Location;
-import org.bukkit.entity.Entity;
-import org.bukkit.plugin.Plugin;
-
-import java.util.Collection;
-
-/**
- * This the main class of the <b>Holographic Displays API</b>.
- * It provides methods to create holograms and to register custom placeholders.
- */
-public class HologramsAPI {
-    
-    
-    private HologramsAPI() {
-        // No constructor needed.
-    }
-    
-    
-    /**
-     * Creates a hologram at given location.
-     * 
-     * @param plugin the plugin that creates it
-     * @param source the location where it will appear
-     * @return the new hologram created
-     */
-    public static Hologram createHologram(Plugin plugin, Location source) {
-        return BackendAPI.getImplementation().createHologram(plugin, source);
-    }
-    
-    
-    /**
-     * Finds all the holograms created by a given plugin.
-     * 
-     * @param plugin the plugin to search for in holograms
-     * @return the holograms created by a plugin. the Collection is a copy
-     * and modifying it has no effect on the holograms.
-     */
-    public static Collection<Hologram> getHolograms(Plugin plugin) {
-        return BackendAPI.getImplementation().getHolograms(plugin);
-    }
-    
-    public static void registerPlaceholder(Plugin plugin, String identifier, int refreshIntervalTicks, PlaceholderReplacer replacer) {
-        BackendAPI.getImplementation().registerPlaceholder(plugin, identifier, refreshIntervalTicks, replacer);
-    }
-    
-    
-    /**
-     * Returns all the placeholder identifiers registered by a given plugin.
-     * 
-     * @param plugin the plugin to search for
-     * @return a collection of placeholder identifiers registered by the plugin
-     */
-    public static Collection<String> getRegisteredPlaceholders(Plugin plugin) {
-        return BackendAPI.getImplementation().getRegisteredPlaceholders(plugin);
-    }
-    
-    
-    /**
-     * Unregister a placeholder created by a plugin.
-     * 
-     * @param plugin the plugin that owns the placeholder
-     * @param identifier the identifier of the placeholder to remove
-     */
-    public static void unregisterPlaceholder(Plugin plugin, String identifier) {
-        BackendAPI.getImplementation().unregisterPlaceholder(plugin, identifier);
-    }
-    
-    
-    /**
-     * Resets and removes all the placeholders registered by a plugin. This is useful
-     * when you have configurable placeholders and you want to remove all of them.
-     * 
-     * @param plugin the plugin that owns the placeholders
-     */
-    public static void unregisterPlaceholders(Plugin plugin) {
-        BackendAPI.getImplementation().unregisterPlaceholders(plugin);
-    }
-    
-    
-    /**
-     * Checks if an entity is part of a hologram.
-     * 
-     * @param bukkitEntity the entity to check
-     * @return true if the entity is a part of a hologram
-     */
-    public static boolean isHologramEntity(Entity bukkitEntity) {
-        return BackendAPI.getImplementation().isHologramEntity(bukkitEntity);
-    }
-
-}

api/src/main/java/me/filoghost/holographicdisplays/api/HolographicDisplaysAPI.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.api;
+
+import me.filoghost.holographicdisplays.api.internal.HolographicDisplaysAPIProvider;
+import me.filoghost.holographicdisplays.api.placeholder.PlaceholderReplacer;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.bukkit.plugin.Plugin;
+
+import java.util.Collection;
+
+/**
+ * Main entry point for accessing the Holographic Displays API.
+ * 
+ * @since 1
+ */
+public interface HolographicDisplaysAPI {
+
+    /**
+     * Returns the API version number, which is increased every time the API changes. This number is used to check if a
+     * certain method or class (which may have been added later) is present or not.
+     * <p>
+     * All public API classes and methods are documented with the Javadoc tag {@code @since}, indicating in which API
+     * version that element was introduced.
+     * <p>
+     * It can be used it to require a minimum version, as features may be added (rarely removed) in future versions. The
+     * first version of the API is 1.
+     * <p>
+     * The API version is independent from the normal plugin version.
+     *
+     * @return the current API version
+     * @since 1
+     */
+    static int getVersion() {
+        return 1;
+    }
+
+    static HolographicDisplaysAPI get(Plugin plugin) {
+        return HolographicDisplaysAPIProvider.getImplementation().getHolographicDisplaysAPI(plugin);
+    }
+
+    /**
+     * Creates a hologram at given location.
+     *
+     * @param source the location where it will appear
+     * @return the created hologram
+     * @since 1
+     */
+    Hologram createHologram(Location source);
+
+    /**
+     * Returns all the active holograms. A hologram is no longer active after {@link Hologram#delete()} is invoked.
+     *
+     * @return an immutable collection of active holograms
+     * @since 1
+     */
+    Collection<Hologram> getHolograms();
+
+    /**
+     * @since 1
+     */
+    void registerPlaceholder(String identifier, int refreshIntervalTicks, PlaceholderReplacer replacer);
+
+    /**
+     * Returns all the registered placeholder identifiers.
+     *
+     * @return a collection of placeholder identifiers
+     * @since 1
+     */
+    Collection<String> getRegisteredPlaceholders();
+
+    /**
+     * Unregisters a placeholder.
+     *
+     * @param identifier the identifier of the placeholder to remove
+     * @since 1
+     */
+    void unregisterPlaceholder(String identifier);
+
+    /**
+     * Resets and removes all the registered placeholders.
+     * <p>
+     * May be useful to invoke before registering all the placeholders of your plugin.
+     * 
+     * @since 1
+     */
+    void unregisterPlaceholders();
+
+    /**
+     * Checks if an entity is part of a hologram.
+     *
+     * @param entity the entity to check
+     * @return if the entity is part of a hologram
+     * @since 1
+     */
+    static boolean isHologramEntity(Entity entity) {
+        return HolographicDisplaysAPIProvider.getImplementation().isHologramEntity(entity);
+    }
+
+}

api/src/main/java/me/filoghost/holographicdisplays/api/VisibilityManager.java

@@ -11,6 +11,8 @@ import org.bukkit.entity.Player;
  * This object is used to manage the visibility of a hologram.
  * It allows to hide/show the hologram to certain players, and the default behaviour
  * (when a hologram is not specifically being hidden/shown to a player) can be customized.
+ * 
+ * @since 1
  */
 public interface VisibilityManager {
     
@@ -19,6 +21,7 @@ public interface VisibilityManager {
      * is true by default so the hologram is visible to everyone.
      * 
      * @return if the hologram hologram is visible by default
+     * @since 1
      */
     boolean isVisibleByDefault();
     
@@ -27,6 +30,7 @@ public interface VisibilityManager {
      * is true by default so the hologram is visible to everyone.
      * 
      * @param visibleByDefault the new behaviour
+     * @since 1
      */
     void setVisibleByDefault(boolean visibleByDefault);
     
@@ -35,6 +39,7 @@ public interface VisibilityManager {
      * This is persistent if the players goes offline.
      * 
      * @param player the involved player
+     * @since 1
      */
     void showTo(Player player);
     
@@ -43,6 +48,7 @@ public interface VisibilityManager {
      * This is persistent if the players goes offline.
      * 
      * @param player the involved player
+     * @since 1
      */
     void hideTo(Player player);
     
@@ -51,6 +57,7 @@ public interface VisibilityManager {
      * 
      * @param player the involved player
      * @return if the player can see the hologram
+     * @since 1
      */
     boolean isVisibleTo(Player player);
     
@@ -60,11 +67,14 @@ public interface VisibilityManager {
      * to reflect the value of {@link #isVisibleByDefault()}.
      * 
      * @param player the involved player
+     * @since 1
      */
     void resetVisibility(Player player);
     
     /**
      * Resets the visibility for all the players. See {@link #resetVisibility(Player)} for more details.
+     * 
+     * @since 1
      */
     void resetVisibilityAll();
     

api/src/main/java/me/filoghost/holographicdisplays/api/handler/PickupHandler.java

@@ -9,12 +9,15 @@ import org.bukkit.entity.Player;
 
 /**
  * Interface to handle items being picked up by players.
+ * 
+ * @since 1
  */
 public interface PickupHandler {
 
     /**
      * Called when a player picks up the item.
      * @param player the player who picked up the item
+     * @since 1
      */
     void onPickup(Player player);
     

api/src/main/java/me/filoghost/holographicdisplays/api/handler/TouchHandler.java

@@ -9,12 +9,15 @@ import org.bukkit.entity.Player;
 
 /**
  * Interface to handle touch holograms.
+ * 
+ * @since 1
  */
 public interface TouchHandler {
 
     /**
      * Called when a player interacts with the hologram (right click).
      * @param player the player who interacts
+     * @since 1
      */
     void onTouch(Player player);
     

api/src/main/java/me/filoghost/holographicdisplays/api/internal/BackendAPI.java

@@ -1,47 +0,0 @@
-/*
- * Copyright (C) filoghost and contributors
- *
- * SPDX-License-Identifier: GPL-3.0-or-later
- */
-package me.filoghost.holographicdisplays.api.internal;
-
-import me.filoghost.holographicdisplays.api.Hologram;
-import me.filoghost.holographicdisplays.api.placeholder.PlaceholderReplacer;
-import org.bukkit.Location;
-import org.bukkit.entity.Entity;
-import org.bukkit.plugin.Plugin;
-
-import java.util.Collection;
-
-public abstract class BackendAPI {
-    
-    private static BackendAPI implementation;
-    
-    public static void setImplementation(BackendAPI implementation) {
-        BackendAPI.implementation = implementation;
-    }
-    
-    public static BackendAPI getImplementation() {
-        if (implementation == null) {
-            throw new IllegalStateException("No API implementation set. Is Holographic Displays enabled?");
-        }
-        
-        return implementation;
-    }
-
-    public abstract Hologram createHologram(Plugin plugin, Location source);
-
-    public abstract Collection<Hologram> getHolograms(Plugin plugin);
-
-    public abstract void registerPlaceholder(Plugin plugin, String identifier, int refreshIntervalTicks, PlaceholderReplacer replacer);
-
-    public abstract Collection<String> getRegisteredPlaceholders(Plugin plugin);
-
-    public abstract void unregisterPlaceholder(Plugin plugin, String identifier);
-
-    public abstract void unregisterPlaceholders(Plugin plugin);
-
-    public abstract boolean isHologramEntity(Entity bukkitEntity);    
-    
-
-}

api/src/main/java/me/filoghost/holographicdisplays/api/internal/HolographicDisplaysAPIProvider.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.api.internal;
+
+import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
+import org.bukkit.entity.Entity;
+import org.bukkit.plugin.Plugin;
+import org.jetbrains.annotations.ApiStatus.Internal;
+
+@Internal
+public abstract class HolographicDisplaysAPIProvider {
+    
+    private static HolographicDisplaysAPIProvider implementation;
+    
+    public static void setImplementation(HolographicDisplaysAPIProvider implementation) {
+        HolographicDisplaysAPIProvider.implementation = implementation;
+    }
+    
+    public static HolographicDisplaysAPIProvider getImplementation() {
+        if (implementation == null) {
+            throw new IllegalStateException("No API implementation set. Is Holographic Displays enabled?");
+        }
+        
+        return implementation;
+    }
+    
+    public abstract HolographicDisplaysAPI getHolographicDisplaysAPI(Plugin plugin);
+    
+    public abstract boolean isHologramEntity(Entity entity);
+
+}

api/src/main/java/me/filoghost/holographicdisplays/api/line/CollectableLine.java

@@ -9,6 +9,8 @@ import me.filoghost.holographicdisplays.api.handler.PickupHandler;
 
 /**
  * A line of a Hologram that can be picked up.
+ * 
+ * @since 1
  */
 public interface CollectableLine extends HologramLine {
     
@@ -16,6 +18,7 @@ public interface CollectableLine extends HologramLine {
      * Sets the PickupHandler for this line.
      * 
      * @param pickupHandler the new PickupHandler, can be null.
+     * @since 1
      */
     void setPickupHandler(PickupHandler pickupHandler);
     
@@ -23,6 +26,7 @@ public interface CollectableLine extends HologramLine {
      * Returns the current PickupHandler of this line.
      * 
      * @return the current PickupHandler, can be null.
+     * @since 1
      */
     PickupHandler getPickupHandler();
     

api/src/main/java/me/filoghost/holographicdisplays/api/line/HologramLine.java

@@ -9,6 +9,8 @@ import me.filoghost.holographicdisplays.api.Hologram;
 
 /**
  * Interface to represent a line in a Hologram.
+ * 
+ * @since 1
  */
 public interface HologramLine {
     
@@ -16,12 +18,15 @@ public interface HologramLine {
      * Returns the parent Hologram of this line.
      * 
      * @return the parent Hologram.
+     * @since 1
      */
     Hologram getParent();
     
     /**
      * Removes this line from the parent Hologram. Since: v2.0.1
      * Do not call if the Hologram has been deleted, an exception will be thrown.
+     * 
+     * @since 1
      */
     void removeLine();
 

api/src/main/java/me/filoghost/holographicdisplays/api/line/ItemLine.java

@@ -7,12 +7,16 @@ package me.filoghost.holographicdisplays.api.line;
 
 import org.bukkit.inventory.ItemStack;
 
+/**
+ * @since 1
+ */
 public interface ItemLine extends CollectableLine, TouchableLine {
 
     /**
      * Returns the ItemStack of this ItemLine.
      * 
      * @return the ItemStack if this ItemLine.
+     * @since 1
      */
     ItemStack getItemStack();
 
@@ -20,6 +24,7 @@ public interface ItemLine extends CollectableLine, TouchableLine {
      * Sets the ItemStack for this ItemLine.
      * 
      * @param itemStack the new item, should not be null.
+     * @since 1
      */
     void setItemStack(ItemStack itemStack);
     

api/src/main/java/me/filoghost/holographicdisplays/api/line/TextLine.java

@@ -5,12 +5,16 @@
  */
 package me.filoghost.holographicdisplays.api.line;
 
+/**
+ * @since 1
+ */
 public interface TextLine extends TouchableLine {
 
     /**
      * Returns the current text of this TextLine.
      * 
      * @return the current text of this line.
+     * @since 1
      */
     String getText();
     
@@ -18,6 +22,7 @@ public interface TextLine extends TouchableLine {
      * Sets the text of this TextLine.
      * 
      * @param text the new text of this line.
+     * @since 1
      */
     void setText(String text);
     

api/src/main/java/me/filoghost/holographicdisplays/api/line/TouchableLine.java

@@ -9,6 +9,8 @@ import me.filoghost.holographicdisplays.api.handler.TouchHandler;
 
 /**
  * A line of a Hologram that can be touched (right click).
+ * 
+ * @since 1
  */
 public interface TouchableLine extends HologramLine {
 
@@ -16,6 +18,7 @@ public interface TouchableLine extends HologramLine {
      * Sets the TouchHandler for this line.
      * 
      * @param touchHandler the new TouchHandler, can be null.
+     * @since 1
      */
     void setTouchHandler(TouchHandler touchHandler);
     
@@ -23,6 +26,7 @@ public interface TouchableLine extends HologramLine {
      * Returns the current TouchHandler of this line.
      * 
      * @return the current TouchHandler, can be null.
+     * @since 1
      */
     TouchHandler getTouchHandler();
     

api/src/main/java/me/filoghost/holographicdisplays/api/placeholder/Placeholder.java

@@ -5,8 +5,14 @@
  */
 package me.filoghost.holographicdisplays.api.placeholder;
 
+/**
+ * @since 1
+ */
 public interface Placeholder extends PlaceholderReplacer {
 
+    /**
+     * @since 1
+     */
     int getRefreshIntervalTicks();
 
 }

api/src/main/java/me/filoghost/holographicdisplays/api/placeholder/PlaceholderFactory.java

@@ -7,8 +7,14 @@ package me.filoghost.holographicdisplays.api.placeholder;
 
 import org.jetbrains.annotations.Nullable;
 
+/**
+ * @since 1
+ */
 public interface PlaceholderFactory {
-    
+
+    /**
+     * @since 1
+     */
     Placeholder getPlaceholder(@Nullable String argument);
     
 }

api/src/main/java/me/filoghost/holographicdisplays/api/placeholder/PlaceholderReplacer.java

@@ -9,6 +9,8 @@ import org.jetbrains.annotations.Nullable;
 
 /**
  * Simple callback to provide a placeholder replacement.
+ * 
+ * @since 1
  */
 @FunctionalInterface
 public interface PlaceholderReplacer {
@@ -21,6 +23,7 @@ public interface PlaceholderReplacer {
      * <b>Warning</b>: this method should be performance efficient, as it may be invoked often.
      *
      * @return the placeholder replacement
+     * @since 1
      */
     String getReplacement(@Nullable String argument);
 

example/death-holograms/src/main/java/me/filoghost/example/deathholograms/DeathHolograms.java

@@ -6,7 +6,7 @@
 package me.filoghost.example.deathholograms;
 
 import me.filoghost.holographicdisplays.api.Hologram;
-import me.filoghost.holographicdisplays.api.HologramsAPI;
+import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.event.EventHandler;
@@ -20,6 +20,8 @@ import java.time.format.DateTimeFormatter;
 public class DeathHolograms extends JavaPlugin implements Listener {
 
     private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("H:mm");
+    
+    private HolographicDisplaysAPI holographicDisplaysAPI;
 
     @Override
     public void onEnable() {
@@ -30,13 +32,14 @@ public class DeathHolograms extends JavaPlugin implements Listener {
             return;
         }
         
+        holographicDisplaysAPI = HolographicDisplaysAPI.get(this);
         Bukkit.getPluginManager().registerEvents(this, this);
     }
     
     
     @EventHandler
     public void onPlayerDeath(PlayerDeathEvent event) {
-        Hologram hologram = HologramsAPI.createHologram(this, event.getEntity().getEyeLocation());
+        Hologram hologram = holographicDisplaysAPI.createHologram(event.getEntity().getEyeLocation());
         
         hologram.appendTextLine(ChatColor.RED + "Player " + ChatColor.GOLD + event.getEntity().getName() + ChatColor.RED + " died here!");
         hologram.appendTextLine(ChatColor.GRAY + "Time of death: " + TIME_FORMATTER.format(Instant.now()));

example/power-ups/src/main/java/me/filoghost/example/powerups/PowerUps.java

@@ -6,7 +6,7 @@
 package me.filoghost.example.powerups;
 
 import me.filoghost.holographicdisplays.api.Hologram;
-import me.filoghost.holographicdisplays.api.HologramsAPI;
+import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
 import me.filoghost.holographicdisplays.api.line.ItemLine;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
@@ -23,7 +23,9 @@ import org.bukkit.potion.PotionEffect;
 import org.bukkit.potion.PotionEffectType;
 
 public class PowerUps extends JavaPlugin implements Listener {
-    
+
+    private HolographicDisplaysAPI holographicDisplaysAPI;
+
     @Override
     public void onEnable() {
         if (!Bukkit.getPluginManager().isPluginEnabled("HolographicDisplays")) {
@@ -32,7 +34,8 @@ public class PowerUps extends JavaPlugin implements Listener {
             this.setEnabled(false);
             return;
         }
-        
+
+        holographicDisplaysAPI = HolographicDisplaysAPI.get(this);
         Bukkit.getPluginManager().registerEvents(this, this);
     }
     
@@ -45,7 +48,7 @@ public class PowerUps extends JavaPlugin implements Listener {
             event.setDroppedExp(0);
             
             // Spawn the floating item with a label.
-            Hologram hologram = HologramsAPI.createHologram(this, event.getEntity().getLocation().add(0.0, 0.9, 0.0));
+            Hologram hologram = holographicDisplaysAPI.createHologram(event.getEntity().getLocation().add(0.0, 0.9, 0.0));
             hologram.appendTextLine(ChatColor.AQUA  + "" + ChatColor.BOLD + "Speed PowerUp");
             ItemLine icon = hologram.appendItemLine(new ItemStack(Material.SUGAR));
             

legacy-api/src/main/java/com/gmail/filoghost/holograms/api/HolographicDisplaysAPI.java

@@ -8,7 +8,6 @@ package com.gmail.filoghost.holograms.api;
 import com.gmail.filoghost.holograms.api.adapter.FloatingItemAdapter;
 import com.gmail.filoghost.holograms.api.adapter.HologramAdapter;
 import me.filoghost.fcommons.Preconditions;
-import me.filoghost.holographicdisplays.api.HologramsAPI;
 import me.filoghost.holographicdisplays.api.line.ItemLine;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
@@ -49,7 +48,7 @@ public class HolographicDisplaysAPI {
         
         validateLocation(source);
         
-        me.filoghost.holographicdisplays.api.Hologram hologram = HologramsAPI.createHologram(plugin, source);
+        me.filoghost.holographicdisplays.api.Hologram hologram = me.filoghost.holographicdisplays.api.HolographicDisplaysAPI.get(plugin).createHologram(source);
         for (String line : lines) {
             hologram.appendTextLine(line);
         }
@@ -63,7 +62,7 @@ public class HolographicDisplaysAPI {
         validateLocation(source);
         validateItem(itemstack);
         
-        me.filoghost.holographicdisplays.api.Hologram hologram = HologramsAPI.createHologram(plugin, source);
+        me.filoghost.holographicdisplays.api.Hologram hologram = me.filoghost.holographicdisplays.api.HolographicDisplaysAPI.get(plugin).createHologram(source);
         ItemLine itemLine = hologram.appendItemLine(itemstack);
         return new FloatingItemAdapter(plugin, hologram, itemLine);
     }
@@ -81,7 +80,7 @@ public class HolographicDisplaysAPI {
         
         validateLocation(source);
         
-        me.filoghost.holographicdisplays.api.Hologram hologram = HologramsAPI.createHologram(plugin, source);
+        me.filoghost.holographicdisplays.api.Hologram hologram = me.filoghost.holographicdisplays.api.HolographicDisplaysAPI.get(plugin).createHologram(source);
         
         hologram.getVisibilityManager().setVisibleByDefault(false);
         if (whoCanSee != null) {
@@ -111,7 +110,7 @@ public class HolographicDisplaysAPI {
         validateLocation(source);
         validateItem(itemstack);
         
-        me.filoghost.holographicdisplays.api.Hologram hologram = HologramsAPI.createHologram(plugin, source);
+        me.filoghost.holographicdisplays.api.Hologram hologram = me.filoghost.holographicdisplays.api.HolographicDisplaysAPI.get(plugin).createHologram(source);
         ItemLine itemLine = hologram.appendItemLine(itemstack);
         
         hologram.getVisibilityManager().setVisibleByDefault(false);
@@ -142,7 +141,7 @@ public class HolographicDisplaysAPI {
     
     @Deprecated
     public static boolean isHologramEntity(Entity bukkitEntity) {
-        return HologramsAPI.isHologramEntity(bukkitEntity);
+        return me.filoghost.holographicdisplays.api.HolographicDisplaysAPI.isHologramEntity(bukkitEntity);
     }
     
     private static void validateLocation(Location loc) {

plugin/src/main/java/me/filoghost/holographicdisplays/DefaultHolographicDisplaysAPI.java

@@ -7,33 +7,30 @@ package me.filoghost.holographicdisplays;
 
 import me.filoghost.fcommons.Preconditions;
 import me.filoghost.holographicdisplays.api.Hologram;
-import me.filoghost.holographicdisplays.api.internal.BackendAPI;
+import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
 import me.filoghost.holographicdisplays.api.placeholder.PlaceholderReplacer;
-import me.filoghost.holographicdisplays.core.nms.NMSManager;
 import me.filoghost.holographicdisplays.object.api.APIHologramManager;
 import me.filoghost.holographicdisplays.placeholder.registry.PlaceholderRegistry;
 import org.bukkit.Bukkit;
 import org.bukkit.Location;
-import org.bukkit.entity.Entity;
 import org.bukkit.plugin.Plugin;
 
 import java.util.Collection;
 
-public class DefaultBackendAPI extends BackendAPI {
+public class DefaultHolographicDisplaysAPI implements HolographicDisplaysAPI {
 
+    private final Plugin plugin;
     private final APIHologramManager apiHologramManager;
-    private final NMSManager nmsManager;
     private final PlaceholderRegistry placeholderRegistry;
 
-    public DefaultBackendAPI(APIHologramManager apiHologramManager, NMSManager nmsManager, PlaceholderRegistry placeholderRegistry) {
+    public DefaultHolographicDisplaysAPI(Plugin plugin, APIHologramManager apiHologramManager, PlaceholderRegistry placeholderRegistry) {
+        this.plugin = plugin;
         this.apiHologramManager = apiHologramManager;
-        this.nmsManager = nmsManager;
         this.placeholderRegistry = placeholderRegistry;
     }
 
     @Override
-    public Hologram createHologram(Plugin plugin, Location source) {
-        Preconditions.notNull(plugin, "plugin");
+    public Hologram createHologram(Location source) {
         Preconditions.notNull(source, "source");
         Preconditions.notNull(source.getWorld(), "source's world");
         Preconditions.checkState(Bukkit.isPrimaryThread(), "Async hologram creation");
@@ -42,7 +39,7 @@ public class DefaultBackendAPI extends BackendAPI {
     }
     
     @Override
-    public void registerPlaceholder(Plugin plugin, String identifier, int refreshIntervalTicks, PlaceholderReplacer replacer) {
+    public void registerPlaceholder(String identifier, int refreshIntervalTicks, PlaceholderReplacer replacer) {
         Preconditions.notNull(identifier, "identifier");
         Preconditions.checkArgument(refreshIntervalTicks >= 0, "refreshIntervalTicks should be positive");
         Preconditions.notNull(replacer, "replacer");
@@ -51,33 +48,24 @@ public class DefaultBackendAPI extends BackendAPI {
     }
 
     @Override
-    public boolean isHologramEntity(Entity bukkitEntity) {
-        Preconditions.notNull(bukkitEntity, "bukkitEntity");
-        return nmsManager.isNMSEntityBase(bukkitEntity);
-    }
-
-    @Override
-    public Collection<Hologram> getHolograms(Plugin plugin) {
-        Preconditions.notNull(plugin, "plugin");
+    public Collection<Hologram> getHolograms() {
         return apiHologramManager.getHologramsByPlugin(plugin);
     }
 
     @Override
-    public Collection<String> getRegisteredPlaceholders(Plugin plugin) {
-        Preconditions.notNull(plugin, "plugin");
+    public Collection<String> getRegisteredPlaceholders() {
         return placeholderRegistry.getRegisteredIdentifiers(plugin);
     }
 
     @Override
-    public void unregisterPlaceholder(Plugin plugin, String identifier) {
-        Preconditions.notNull(plugin, "plugin");
+    public void unregisterPlaceholder(String identifier) {
         Preconditions.notNull(identifier, "identifier");
+        
         placeholderRegistry.unregister(plugin, identifier);
     }
 
     @Override
-    public void unregisterPlaceholders(Plugin plugin) {
-        Preconditions.notNull(plugin, "plugin");
+    public void unregisterPlaceholders() {
         placeholderRegistry.unregisterAll(plugin);
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/DefaultHolographicDisplaysAPIProvider.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays;
+
+import me.filoghost.fcommons.Preconditions;
+import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
+import me.filoghost.holographicdisplays.api.internal.HolographicDisplaysAPIProvider;
+import me.filoghost.holographicdisplays.core.nms.NMSManager;
+import me.filoghost.holographicdisplays.object.api.APIHologramManager;
+import me.filoghost.holographicdisplays.placeholder.registry.PlaceholderRegistry;
+import org.bukkit.entity.Entity;
+import org.bukkit.plugin.Plugin;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+public class DefaultHolographicDisplaysAPIProvider extends HolographicDisplaysAPIProvider {
+
+    private final APIHologramManager apiHologramManager;
+    private final NMSManager nmsManager;
+    private final PlaceholderRegistry placeholderRegistry;
+    
+    // Avoid creating a new instance every time a plugin requires it
+    private final Map<Plugin, HolographicDisplaysAPI> apiCache;
+
+    public DefaultHolographicDisplaysAPIProvider(APIHologramManager apiHologramManager, NMSManager nmsManager, PlaceholderRegistry placeholderRegistry) {
+        this.apiHologramManager = apiHologramManager;
+        this.nmsManager = nmsManager;
+        this.placeholderRegistry = placeholderRegistry;
+        this.apiCache = new WeakHashMap<>();
+    }
+
+    @Override
+    public HolographicDisplaysAPI getHolographicDisplaysAPI(Plugin plugin) {
+        Preconditions.notNull(plugin, "plugin");
+        
+        return apiCache.computeIfAbsent(plugin, pluginKey ->
+                new DefaultHolographicDisplaysAPI(pluginKey, apiHologramManager, placeholderRegistry));
+    }
+
+    @Override
+    public boolean isHologramEntity(Entity entity) {
+        Preconditions.notNull(entity, "entity");
+        
+        return nmsManager.isNMSEntityBase(entity);
+    }
+
+}

plugin/src/main/java/me/filoghost/holographicdisplays/HolographicDisplays.java

@@ -9,7 +9,7 @@ import me.filoghost.fcommons.FCommonsPlugin;
 import me.filoghost.fcommons.FeatureSupport;
 import me.filoghost.fcommons.config.exception.ConfigException;
 import me.filoghost.fcommons.logging.ErrorCollector;
-import me.filoghost.holographicdisplays.api.internal.BackendAPI;
+import me.filoghost.holographicdisplays.api.internal.HolographicDisplaysAPIProvider;
 import me.filoghost.holographicdisplays.bridge.bungeecord.BungeeServerTracker;
 import me.filoghost.holographicdisplays.bridge.protocollib.ProtocolLibHook;
 import me.filoghost.holographicdisplays.commands.HologramCommandManager;
@@ -123,7 +123,10 @@ public class HolographicDisplays extends FCommonsPlugin implements ProtocolPacke
         registerListener(updateNotificationListener);
         
         // Enable the API.
-        BackendAPI.setImplementation(new DefaultBackendAPI(apiHologramManager, nmsManager, placeholderManager.getPlaceholderRegistry()));
+        HolographicDisplaysAPIProvider.setImplementation(new DefaultHolographicDisplaysAPIProvider(
+                apiHologramManager,
+                nmsManager,
+                placeholderManager.getPlaceholderRegistry()));
 
         // Register bStats metrics
         int pluginID = 3123;