Listener Already Listening

I tried to open an inventory when a Player joined, but it produces an Internal Server Error whenever someone tries to connect:

Code:

[15:44:59 INFO]: UUID of player FlareLine is 6c7ec3d9036c45269de918497bb28095
[15:44:59 INFO]: Loaded player file for FlareLine
[15:44:59 WARN]: Failed to handle packet for /127.0.0.1:17059
java.lang.IllegalArgumentException: Listener already listening
        at net.minecraft.server.v1_7_R2.Container.addSlotListener(Container.java
:53) ~[craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.EntityPlayer.syncInventory(EntityPlayer.
java:151) ~[craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jn
ks]
        at net.minecraft.server.v1_7_R2.PlayerList.a(PlayerList.java:132) ~[craf
tbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.LoginListener.c(LoginListener.java:78) ~
[craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.LoginListener.a(LoginListener.java:42) ~
[craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.NetworkManager.a(NetworkManager.java:150
) ~[craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.ServerConnection.c(SourceFile:134) [craf
tbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.MinecraftServer.v(MinecraftServer.java:6
57) [craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.DedicatedServer.v(DedicatedServer.java:2
50) [craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.MinecraftServer.u(MinecraftServer.java:5
48) [craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.MinecraftServer.run(MinecraftServer.java
:459) [craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
        at net.minecraft.server.v1_7_R2.ThreadServerApplication.run(SourceFile:6
18) [craftbukkit-1.7.5-R0.1.jar:git-Bukkit-1.7.2-R0.3-10-gcf5a547-b3035jnks]
[15:45:00 INFO]: FlareLine lost connection: Internal server error
[15:45:00 INFO]: Removing player from memory: FlareLine
[15:45:00 INFO]: FlareLine left the game.

I'm not sure what is wrong, as I've done this plenty of times before.

 

how random people from forum expected to help you without any code posted?

well i can guess - this is lupus, but it wont help you.

 

RawCode There's really no need to be rude. If you require code to help me find a solution then ask for it, don't just ramble on about how you can't fix it.

 

FlareLine How about posting your listener?

 

No code, no help.

 

You have somehow registered you listener twice.

 

I have asked you to provide code already, you will have issues IRL if can't understand so obvious sarcasm.

 

This is the entire listener class

Show Spoiler Hide Spoiler

Code:java

package me.genki.ms.team;
 
import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.DyeColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
 
@SuppressWarnings("deprecation")
public class OpenGUI implements Listener {
 
    public ItemStack REDWOOL = new ItemStack(Material.WOOL, 1, DyeColor.RED.getData());
    public ItemStack GREENWOOL = new ItemStack(Material.WOOL, 1, DyeColor.GREEN.getData());
    public ItemStack BLUEWOOL = new ItemStack(Material.WOOL, 1, DyeColor.CYAN.getData());
 
    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent ev){
        try {
        Player p = ev.getPlayer();
 
        Inventory i = Bukkit.getServer().createInventory(null, 36, ChatColor.GOLD + "Choos a Faction");
 
        ItemMeta RM = REDWOOL.getItemMeta();
        RM.setDisplayName(ChatColor.RED + "Red Team");
        REDWOOL.setItemMeta(RM);
        ItemMeta GM = GREENWOOL.getItemMeta();
        GM.setDisplayName(ChatColor.GREEN + "Green Team");
        GREENWOOL.setItemMeta(GM);
        ItemMeta BM = BLUEWOOL.getItemMeta();
        BM.setDisplayName(ChatColor.BLUE + "Blue Team");
        BLUEWOOL.setItemMeta(BM);
 
        i.setItem(10, REDWOOL);
        i.setItem(13, GREENWOOL);
        i.setItem(16, BLUEWOOL);
 
        p.openInventory(i);
 
        } catch (Exception e){
            e.printStackTrace();
        }
    }
}
 

 

FlareLine Show your main class; i'm sure there won't be much in your listener class.

 

Maurdekye All that is related to ShowGUI:

Code:java

package me.genki.ms;
 
import me.genki.ms.team.Armour;
import me.genki.ms.team.GameHandler;
import me.genki.ms.team.OpenGUI;
 
import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.entity.Player;
import org.bukkit.plugin.PluginManager;
import org.bukkit.plugin.java.JavaPlugin;
 
public class MineSide extends JavaPlugin {
 
public GameHandler gh = new GameHandler();
public Armour am = new Armour();
public PluginManager pm = getServer().getPluginManager();
public FileConfiguration config;
public OpenGUI gui = new OpenGUI(); // Related Instance
 
public void onEnable() {
 
pm.registerEvents(gui, this); // Related Register Events
am.addItems();
saveDefaultConfig();
}
 
public void onDisable() {
 
}
}
 

Please excuse the messy formatting.

Update:

I just found out that I can join the server fine, and the GUI pops up. However, after about half a second, I get kicked because of this "Internal Server Error".

 

not going to spoonfeed you, add some debug output atleast.

this is little spoiler about source of issue.

Code:

    public void addSlotListener(ICrafting icrafting) {
        if (this.listeners.contains(icrafting)) {
            throw new IllegalArgumentException("Listener already listening");
        } else {
            this.listeners.add(icrafting);
            icrafting.a(this, this.a());
            this.b();
        }
    }

 

RawCode I figure that this is called whenever I register a Listener. Therefore, I'm thinking that somehow I have two instances of OpenGUI appearing somewhere in my code.
That is correct right?

 

No that is not the issue, but it would seem like it. I have had this one before and it's somewhat tricky to understand. It is not complaining about YOUR listener, but rather an internal one which you do not need to worry about. This error occurs when you try to open an inventory on a player who hasn't fully joined yet. Adding a delay before opening the inv should do it

 

Rocoty This doesn't seem to be the case though, as the inventory is loaded on screen after I've joined before the server kicks me.

 

FlareLine would you like to try though?

 

Rocoty I'll get back to you with the results

Edit: That's got it, however I might try to do it another way completely removing the need to open an inventory when the play joins, as I need it to come up immediately after the player has loaded and before they can do anything - in a broader term, forcing them to use the GUI as soon as they join.
Cheers

 

FlareLine The reason it was failing is because the event is called before the player actually joins, so the server breaks. That's why the delay works.

 

Maurdekye Is there a reason it was working and then I got an error?

 

FlareLine Possibly because the client had loaded up, but the event was called just before the server was completely ready with the player. So it showed for just a half second on the client before the server realized that it couldn't show you any kind of serverside information. All just speculation, though.

 

Maurdekye I get it now.

 

FlareLine Maurdekye Yeah. Basically we don't know...and everyone is too lazy to check through tons of NMS/Craftbukkit source to find out why it happens. Just know that it happens and what to do to prevent it. A delay of one tick is enough I think. If not, maybe two.

 

Try doing a small Delayed Task after the PlayerJoinEvent, and then showing up the GUI.
Edit: Ninja'd

 

Rocoty Ah just a couple of ticks, I was thinking like 1 or 2 seconds but I'll go and change that.

MOMOTHEREAL I kinda figured that from previous posts, but thanks for your help.

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

 

FlareLine 1 tick should be more than enough in all situations. It's not like a variable delay; the event is just a method called alongside the code when a player joins the game.

 

Maurdekye I see, it's just more than one method conflicting.

 

Maurdekye Unless of course the event is async...then you're in trouble.