I am getting a nullpointerexception whenever I use Bukkit's "containsEnchantment()" method, which supposedly returns a boolean. The purpose of this code snippet is to check if an item in a player's inventory has an enchantment higher than 5.
My log tells that a nullpointer exception is being thrown at line 408. In my code I have left a comment at line 408.
I tried playing around with other methods to check if the item had enchantments; however I got an export error whenever I used "getEnchantments()." I compile and export my plugin in Eclipse and then use jd-GUI to decompile it for the purpose of checking for corruptness. When I use getEnchantments() : java.util.Map, jd-GUI displays //INTERNAL ERROR// when I decompile my .jar. Using Maps does not work with Bukkit.
I do not understand why my code does not work. The variable "player" is the type org.Bukkit.entity.Player.
Here is some of my code:
boolean illegalEnchants = false;
ArrayList<ItemStack> stacks = new ArrayList<ItemStack>();
Inventory i = player.getInventory();
if(i.getContents() != null){
for(ItemStack inven : i.getContents()){
ArrayList<Integer> enchants = new ArrayList<Integer>();
if(inven.containsEnchantment(Enchantment.ARROW_DAMAGE)){ //LINE 408
enchants.add(inven.getEnchantmentLevel(Enchantment.ARROW_DAMAGE));
}
if(inven.containsEnchantment(Enchantment.ARROW_FIRE)){
enchants.add(inven.getEnchantmentLevel(Enchantment.ARROW_FIRE));
}
if(inven.containsEnchantment(Enchantment.ARROW_INFINITE)){
enchants.add(inven.getEnchantmentLevel(Enchantment.ARROW_INFINITE));
}
if(inven.containsEnchantment(Enchantment.ARROW_KNOCKBACK)){
enchants.add(inven.getEnchantmentLevel(Enchantment.ARROW_KNOCKBACK));
}
if(inven.containsEnchantment(Enchantment.DAMAGE_ALL)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DAMAGE_ALL));
}
if(inven.containsEnchantment(Enchantment.DAMAGE_ARTHROPODS)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DAMAGE_ARTHROPODS));
}
if(inven.containsEnchantment(Enchantment.DAMAGE_UNDEAD)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DAMAGE_UNDEAD));
}
if(inven.containsEnchantment(Enchantment.DEPTH_STRIDER)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DEPTH_STRIDER));
}
if(inven.containsEnchantment(Enchantment.DIG_SPEED)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DIG_SPEED));
}
if(inven.containsEnchantment(Enchantment.DURABILITY)){
enchants.add(inven.getEnchantmentLevel(Enchantment.DURABILITY));
}
if(inven.containsEnchantment(Enchantment.FIRE_ASPECT)){
enchants.add(inven.getEnchantmentLevel(Enchantment.FIRE_ASPECT));
}
if(inven.containsEnchantment(Enchantment.KNOCKBACK)){
enchants.add(inven.getEnchantmentLevel(Enchantment.KNOCKBACK));
}
if(inven.containsEnchantment(Enchantment.LOOT_BONUS_BLOCKS)){
enchants.add(inven.getEnchantmentLevel(Enchantment.LOOT_BONUS_BLOCKS));
}
if(inven.containsEnchantment(Enchantment.LOOT_BONUS_MOBS)){
enchants.add(inven.getEnchantmentLevel(Enchantment.LOOT_BONUS_MOBS));
}
if(inven.containsEnchantment(Enchantment.LUCK)){
enchants.add(inven.getEnchantmentLevel(Enchantment.LUCK));
}
if(inven.containsEnchantment(Enchantment.OXYGEN)){
enchants.add(inven.getEnchantmentLevel(Enchantment.OXYGEN));
}
if(inven.containsEnchantment(Enchantment.LURE)){
enchants.add(inven.getEnchantmentLevel(Enchantment.LURE));
}
if(inven.containsEnchantment(Enchantment.PROTECTION_ENVIRONMENTAL)){
enchants.add(inven.getEnchantmentLevel(Enchantment.PROTECTION_ENVIRONMENTAL));
}
if(inven.containsEnchantment(Enchantment.PROTECTION_EXPLOSIONS)){
enchants.add(inven.getEnchantmentLevel(Enchantment.PROTECTION_EXPLOSIONS));
}
if(inven.containsEnchantment(Enchantment.PROTECTION_FALL)){
enchants.add(inven.getEnchantmentLevel(Enchantment.PROTECTION_FALL));
}
if(inven.containsEnchantment(Enchantment.PROTECTION_FIRE)){
enchants.add(inven.getEnchantmentLevel(Enchantment.PROTECTION_FIRE));
}
if(inven.containsEnchantmen(tEnchantment.PROTECTION_PROJECTILE)){
enchants.add(inven.getEnchantmentLevel(Enchantment.PROTECTION_PROJECTILE));
}
if(inven.containsEnchantment(Enchantment.SILK_TOUCH)){
enchants.add(inven.getEnchantmentLevel(Enchantment.SILK_TOUCH));
}
if(inven.containsEnchantment(Enchantment.THORNS)){
enchants.add(inven.getEnchantmentLevel(Enchantment.THORNS));
}
if(inven.containsEnchantment(Enchantment.WATER_WORKER)){
enchants.add(inven.getEnchantmentLevel(Enchantment.WATER_WORKER));
}
for(int j : enchants){
if(j > 5){
illegalEnchants = true;
stacks.add(inven);
}
}
}
}
for(ItemStack is : stacks){
i.removeItem(is);
}
Here is my server log:
10.03 21:54:54 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at me.pyro.main.Main.onCommand(Main.java:408) ~[?:?] 10.03 21:54:54 [Server] INFO Caused by: java.lang.NullPointerException 10.03 21:54:54 [Server] INFO at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:536) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:628) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:335) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:672) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_45] 10.03 21:54:54 [Server] INFO at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_45] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(SourceFile:9) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(SourceFile:37) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:966) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1106) [craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:620) ~[craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140) ~[craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit.jar:git-Bukkit-880a532] 10.03 21:54:54 [Server] INFO org.bukkit.command.CommandException: Unhandled exception executing command 'removeitems' in plugin AntiInventoryCheat v1.8 10.03 21:54:54 [Server] ERROR null
Line 408 (and all other lines referencing inven) in your code can throw a NullPointerException because the ItemStack in the inventory you're iterating through can be null in the case of an empty slot. A null-check will fix this, for example:
for (ItemStack item : inventory.getContents()) {
if (item == null) {
continue;
}
// Your enchantment code here
}