Solved Enchantment Glow w/o actual enchantment

Hello!

Im creating a minigame plugin, and im trying to add a purple enchantment glow to an itemstack.
I can add it perfectly (w/o errors). But when I interact with this itemstack I get disconnected from the server.

Any ideas ?

Error

Code:

[19:51:09 INFO]: HeyImFat lost connection: Internal Exception: net.minecraft.util.
io.netty.handler.codec.DecoderException: java.lang.NullPointerException

EnchantGlow class (source not by me)

Code:java

public class EnchantGlow extends EnchantmentWrapper {
 
    public EnchantGlow(int id) {
        super(id);
    }
 
    @Override
    public boolean canEnchantItem(ItemStack item) {
        return true;
    }
 
    @Override
    public boolean conflictsWith(Enchantment other) {
        return false;
    }
 
    @Override
    public EnchantmentTarget getItemTarget() {
        return null;
    }
 
    @Override
    public int getMaxLevel() {
        return 10;
    }
 
    @Override
    public String getName() {
        return "Glow";
    }
 
    @Override
    public int getStartLevel() {
        return 1;
    }
 
}

Adding to itemstack

Code:java

private ItemStack convertWithEnchantment(ItemStack stack) {
        EnchantGlow glow = new EnchantGlow(120);
        try {
            stack.addUnsafeEnchantment(glow, 1);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return stack;
    }

 

Okay there is a way through protocollib but I don't know it, can we see full error?

 

Unica Try this.

Code:java

import org.bukkit.enchantments.Enchantment;
import org.bukkit.enchantments.EnchantmentTarget;
import org.bukkit.enchantments.EnchantmentWrapper;
import org.bukkit.inventory.ItemStack;
 
import java.lang.reflect.Field;
 
public class Glow extends EnchantmentWrapper {
 
    private static Enchantment glow;
 
    public Glow(int id) {
        super(id);
    }
 
    @Override
    public boolean canEnchantItem(ItemStack item) {
        return true;
    }
 
    @Override
    public boolean conflictsWith(Enchantment other) {
        return false;
    }
 
    @Override
    public EnchantmentTarget getItemTarget() {
        return null;
    }
 
    @Override
    public int getMaxLevel() {
        return 10;
    }
 
    @Override
    public String getName() {
        return "Glow";
    }
 
    @Override
    public int getStartLevel() {
        return 1;
    }
 
    public static Enchantment getGlow() {
        if(glow != null)
            return glow;
        try {
            Field f = Enchantment.class.getDeclaredField("acceptingNew");
            f.setAccessible(true);
            f.set(null, true);
        } catch(Exception e) {
            e.printStackTrace();
        }
        glow = new Glow(255);
        Enchantment.registerEnchantment(glow);
        return glow;
    }
 
    public static void addGlow(ItemStack item) {
        Enchantment glow = getGlow();
        item.addEnchantment(glow, 1);
    }
}

Code:java

 
//Made without IDE, probably some error here, but you get the gist of it
ItemStack is = new ItemStack(Material.STONE);
Glow.addGlow(is);
 
if (is.containsEnchantment(Glow.getGlow())
  is.removeEnchantment(Glow.getGlow());

 

97WaterPolo

Thanks! Will try once I get home

mine-care
Haha, the funny thing is that this is the entire stacktrace

97WaterPolo

Works like a charm!
Thanks

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Unica
Glad to see that it works! Thank SoThatsIt for that awesome class!

 

97WaterPolo

Hey, sorry for bothering you again, but there seems to occur a error.

Code:

Caused by: java.lang.IllegalArgumentException: Cannot set already-set enchantmen
t
        at org.bukkit.enchantments.Enchantment.registerEnchantment(Enchantment.j
ava:236) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at me.dubehh.Mech.Glow.getGlow(Glow.java:59) ~[?:?]
        at me.dubehh.GamePlay.GUI.MeleeMenu.convertWithEnchantment(MeleeMenu.jav
a:64) ~[?:?]
        at me.dubehh.GamePlay.GUI.MeleeMenu.openMeleeInventory(MeleeMenu.java:48
) ~[?:?]
        at me.dubehh.Listeners.InventoryClick.onClick(InventoryClick.java:61) ~[
?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0
_67]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0
_67]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_67]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_67]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:292) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        ... 13 more

ConvertWithEnchantment

Code:java

private ItemStack convertWithEnchantment(ItemStack stack) {
        if(stack.containsEnchantment(Glow.getGlow())){
            stack.removeEnchantment(Glow.getGlow());
        }
        Glow.addGlow(stack);
        return stack;
    }

I did not change a thing on that other class,
and I understand the error Cannot set already-set enchantmen
t , but I thought removing it first, then adding it would fix that

 

Unica
Um what you did is correct I believe, try recompiling it, that method should work. Is there another place you are calling it and just happened to forget to check if it has a glow already?

 

97WaterPolo

Hey, This is the only place where I actually use the Glow thing.
I've found when the error appears,
it seems that when the first time my inventory menu get's opened (after a reload / restart) the error appears, after that the error only appears after a new reload.

 

Unica check if the Enchantment is registered before attempting to register it. After the != null check, try getting the enchantment from Enchantment. If that returns null, register it.

 

fireblast709
Hey, Could u be a little bit more specific? Maybe with some pseudo code? I don't know exactly what u mean

 

Unica Assuming we know 'id' (basically the id of your enchantment)

Code:

ench = getById(id)
if(ench != null) // Thus, it was registered already!
    return;
// Here you register your enchantment

 

fireblast709

Should this be called in the onEnable, ur when I call my method?

 

Unica this is basically the behaviour of getGlow(). The fundamental difference is that you check if your static field is set, whereas I check if the Enchantment is actually registered.

When you reload, that static field is garbage collected (and thus null), but the Enchantment is not unregistered. Then later you try to register it again (because that static field is null). But wait, it was already registered... this leads to the error that you are getting.

 

fireblast709
Hello sir, thanks for your reply and explanation, the bad thing is that still fail to create this correctly,

Method

Code:java

@SuppressWarnings("deprecation")
    private ItemStack convertWithEnchantment(ItemStack stack) {
        Enchantment ench = Enchantment.getById(255); //Id is 255 which is set in the Glow class?
        if (ench != null) {
            System.out.println("Not null ;)");
            return stack;
        }
        Enchantment.registerEnchantment(Enchantment.getById(255));
        if (stack.containsEnchantment(Glow.getGlow())) {
            stack.removeEnchantment(Glow.getGlow());
        }
        Glow.addGlow(stack);
        return stack;
    }

Error after fresh server startup

Code:

[22:52:49 ERROR]: Could not pass event InventoryClickEvent to Strikerz v0.1
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:294) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:501) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PlayerConnection.a(PlayerConnection.java
:1363) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInWindowClick.a(SourceFile:32)
[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInWindowClick.handle(SourceFil
e:10) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.NetworkManager.a(NetworkManager.java:157
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.ServerConnection.c(SourceFile:134) [craf
tbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:6
67) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:2
60) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:5
58) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java
:469) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:6
28) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
Caused by: java.lang.NullPointerException
        at org.bukkit.enchantments.Enchantment.registerEnchantment(Enchantment.j
ava:235) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at me.dubehh.GamePlay.GUI.MeleeMenu.convertWithEnchantment(MeleeMenu.jav
a:70) ~[?:?]
        at me.dubehh.GamePlay.GUI.MeleeMenu.openMeleeInventory(MeleeMenu.java:49
) ~[?:?]
        at me.dubehh.Listeners.InventoryClick.onClick(InventoryClick.java:61) ~[
?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0
_67]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0
_67]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_67]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_67]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:292) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        ... 13 more

Problem after /reload
The debug message (not null ) gets fired, which means java assumes it's not null, I am certainly missing something

 

Unica you try tot register null. (Since you know that Enchantment.getById(255) is null after line 7). Instead, create your EnchantmentWrapper there

 

fireblast709

Hello sir,
Im really trying to understand this,

Current problem: After a fresh restart, the enchantment works, but when I re-open my inventory menu, the enchantment is gone.
Known cause: After a restart (not /reload) the 'ench' is no longer null, which means it breaks out of the code.
So it returns the normal itemstack because it's not null. I tried different things inside this method, and I would really appreciate some pseudo code / push in the right direction.

I am (decent) experienced in java / bukkit developing, it's just that I've never used this kind of stuff.

EDIT:

Code:java

@SuppressWarnings("deprecation")
    private ItemStack convertWithEnchantment(ItemStack stack) {
        Enchantment ench = Enchantment.getById(255);
        if (ench != null) {
            return stack;
        }
        if (stack.containsEnchantment(Glow.getGlow())) {
            stack.removeEnchantment(Glow.getGlow());
        }
        Glow.addGlow(stack);
        return stack;
    }

 

Unica I just noticed you were editing convertWithEnchantment instead of getGlow

 

fireblast709
aah lol
So where should I put your earlier fix?

 

Unica in getGlow() (since you were initializing it there)

 

fireblast709
Hey,
I think all checks are done right?
Im still getting the IllegalArgumentException

Code:java

 public static Enchantment getGlow() {
        if(glow != null)
            return glow;
        try {
            Field f = Enchantment.class.getDeclaredField("acceptingNew");
            f.setAccessible(true);
            f.set(null, true);
        } catch(Exception e) {
            e.printStackTrace();
        }
        glow = new Glow(255);
        Enchantment.registerEnchantment(glow); //Glow is null, can't register (obviously)
        return glow;
    }

Im not sure how to make that glow NOT null..

 

Unica before the if statement, add

Code:java

if(glow != null)
    return glow;
Enchantment g = Enchantment.getById(255);
if(g instanceof Glow)
{
    glow = (Glow) g;
    return glow;
}
// here you add the rest of your code, starting with the try-catch

(Though note, if g isn't an instance of Glow, you need to handle that accordingly )

 

fireblast709
Hey, thanks for all your replies, but it seems it doesn't work.

Code:java

@SuppressWarnings("deprecation")
    public static Enchantment getGlow() {
        Enchantment g = Enchantment.getById(255);
        if (g instanceof Glow) {
            glow = (Glow) g;
            if (glow != null)
                return glow;
            try {
                Field f = Enchantment.class.getDeclaredField("acceptingNew");
                f.setAccessible(true);
                f.set(null, true);
            } catch (Exception e) {
                e.printStackTrace();
            }
            glow = new Glow(255);
            Enchantment.registerEnchantment(glow);
            return glow;
        } else {
            return Enchantment.getById(255); //Is null on first ever start so yea.
        }
    }

On reloads, this works fine, but on the first ever start of the server the enchantment is null so I keep getting a "Enchantment cannot be null error".

Code:

[17:14:44 ERROR]: Could not pass event InventoryClickEvent to Strikerz v0.1
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:294) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:501) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PlayerConnection.a(PlayerConnection.java
:1363) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInWindowClick.a(SourceFile:32)
 [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInWindowClick.handle(SourceFil
e:10) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.NetworkManager.a(NetworkManager.java:157
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.ServerConnection.c(SourceFile:134) [craf
tbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:6
67) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:2
60) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:5
58) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java
:469) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:6
28) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
Caused by: java.lang.IllegalArgumentException: Enchantment cannot be null
        at org.apache.commons.lang.Validate.notNull(Validate.java:203) ~[craftbu
kkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at org.bukkit.inventory.ItemStack.addEnchantment(ItemStack.java:428) ~[c
raftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        at me.dubehh.Mech.Glow.addGlow(Glow.java:75) ~[?:?]
        at me.dubehh.GamePlay.GUI.MeleeMenu.convertWithEnchantment(MeleeMenu.jav
a:63) ~[?:?]
        at me.dubehh.GamePlay.GUI.MeleeMenu.openMeleeInventory(MeleeMenu.java:48
) ~[?:?]
        at me.dubehh.Listeners.InventoryClick.onClick(InventoryClick.java:66) ~[
?:?]
        at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_67]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_67]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:292) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-56-g3779cff-b3072jnks]
        ... 13 more
>

 

Unica nonono xD. Let me add some braces for clarification (so check my previous post in a minute or two)

 

Do you even Glow?

 

Marten Mooij
Baby don't hurt me. No more.

fireblast709
The error appeared again
I looked through jd.bukkit.org for possible fixes and I found Enchantment.values, which returns a list of all enchantments.

Using that I did

Code:java

for(Enchantment e : Enchantment.values()){
            if(e.equals(glow))
                return glow;
        }

Before I registered which worked