Avoid unintentionally loading loads of chunks with Location#getChunk

api/src/main/java/net/jitse/npclib/listeners/ChunkListener.java

@@ -9,12 +9,14 @@ import net.jitse.npclib.internal.NPCManager;
 import net.jitse.npclib.internal.SimpleNPC;
 import org.bukkit.Bukkit;
 import org.bukkit.Chunk;
+import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
 import org.bukkit.event.world.ChunkLoadEvent;
 import org.bukkit.event.world.ChunkUnloadEvent;
 
+import java.util.Objects;
 import java.util.UUID;
 
 /**
@@ -33,11 +35,10 @@ public class ChunkListener implements Listener {
         Chunk chunk = event.getChunk();
 
         for (SimpleNPC npc : NPCManager.getAllNPCs()) {
-            Chunk npcChunk = npc.getLocation().getChunk();
+            if (!isSameChunk(npc.getLocation(), chunk))
-
+                continue; // We aren't unloading the chunk with the NPC in it.
-            if (chunk.equals(npcChunk)) {
-                // Unloaded chunk with NPC in it. Hiding it from all players currently shown to.
 
+            // We found an NPC in the chunk being unloaded. Time to hide this NPC from all players.
             for (UUID uuid : npc.getShown()) {
                 // Safety check so it doesn't send packets if the NPC has already
                 // been automatically despawned by the system.
@@ -49,18 +50,16 @@ public class ChunkListener implements Listener {
             }
         }
     }
-    }
 
     @EventHandler
     public void onChunkLoad(ChunkLoadEvent event) {
         Chunk chunk = event.getChunk();
 
         for (SimpleNPC npc : NPCManager.getAllNPCs()) {
-            Chunk npcChunk = npc.getLocation().getChunk();
+            if (!isSameChunk(npc.getLocation(), chunk))
-
+                continue; // The NPC is not in the loaded chunk.
-            if (chunk.equals(npcChunk)) {
-                // Loaded chunk with NPC in it. Showing it to the players again.
 
+            // The chunk being loaded has this NPC in it. Showing it to all the players again.
             for (UUID uuid : npc.getShown()) {
                 // Make sure not to respawn a not-hidden NPC.
                 if (!npc.getAutoHidden().contains(uuid)) {
@@ -68,8 +67,10 @@ public class ChunkListener implements Listener {
                 }
 
                 Player player = Bukkit.getPlayer(uuid);
+                if (player == null)
+                    continue; // Couldn't find the player, so skip.
 
-                    if (!npcChunk.getWorld().equals(player.getWorld())) {
+                if (!Objects.equals(npc.getWorld(), player.getWorld())) {
                     continue; // Player and NPC are not in the same world.
                 }
 
@@ -84,5 +85,16 @@ public class ChunkListener implements Listener {
             }
         }
     }
+
+
+    private static int getChunkCoordinate(int coordinate) {
+        return coordinate >> 4;
+    }
+
+    // Using Location#getChunk will load the chunk, which is a pretty hefty task, so we'll want to avoid it.
+    // Using Location#getChunk would effectively mean we'd load every chunk an NPC is located in when any chunk is unloaded.
+    private static boolean isSameChunk(Location loc, Chunk chunk) {
+        return getChunkCoordinate(loc.getBlockX()) == chunk.getX()
+                && getChunkCoordinate(loc.getBlockZ()) == chunk.getZ();
     }
 }