I'm making a plugin and got an error executing a cmd.

Code:

[15:05:01] [Server thread/INFO]: Sarcry issued server command: /staffon
[15:05:01] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'staffon' in plugin StaffPl v1.0
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:139) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.craftbukkit.v1_10_R1.CraftServer.dispatchCommand(CraftServer.java:625) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PlayerConnection.handleCommand(PlayerConnection.java:1299) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PlayerConnection.a(PlayerConnection.java:1159) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PacketPlayInChat.a(SourceFile:37) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PacketPlayInChat.a(SourceFile:9) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PlayerConnectionUtils$1.run(SourceFile:13) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_101]
    at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_101]
    at net.minecraft.server.v1_10_R1.SystemUtils.a(SourceFile:45) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:688) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:361) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:643) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:547) [craftbukkit.jar:git-Bukkit-5e5cf84]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_101]
Caused by: java.lang.IllegalArgumentException: Plugin already initialized!
    at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader.java:98) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at me.certe.Certe.<init>(Certe.java:11) ~[?:?]
    at me.certe.Mod.<init>(Mod.java:20) ~[?:?]
    at me.certe.Certe.onCommand(Certe.java:27) ~[?:?]
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    ... 15 more
Caused by: java.lang.IllegalStateException: Initial initialization
    at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader.java:101) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at me.certe.Certe.<init>(Certe.java:11) ~[?:?]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_101]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_101]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_101]
    at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.8.0_101]
    at java.lang.Class.newInstance(Unknown Source) ~[?:1.8.0_101]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:52) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:328) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.craftbukkit.v1_10_R1.CraftServer.loadPlugins(CraftServer.java:294) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at org.bukkit.craftbukkit.v1_10_R1.CraftServer.<init>(CraftServer.java:256) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.PlayerList.<init>(PlayerList.java:70) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.DedicatedPlayerList.<init>(SourceFile:14) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.DedicatedServer.init(DedicatedServer.java:184) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:514) ~[craftbukkit.jar:git-Bukkit-5e5cf84]
    ... 1 more

 

@Sarcry
You are somehow creating a new instance of your main class, I can't tell you much more without seeing your code.

 

how to read stack traces and troubleshoot your own plugins by yourself

Do people even know what sticky posts there are??

 

http://pastebin.com/jAYWVXhx

if you need the Mod class code ask me

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

 

@Sarcry
Can you show me the other two classes?

 

http://pastebin.com/mqRpG1J0
http://pastebin.com/Ybqv9BbW

 

Realized that was the little problem but now other one surged. I execute the command(in this case /staffon or /staffoff) and apears for first time on the chat and then I execute the cmd again and gives me the stuff twice and they dont have their names I set.

 

@Sarcry
As @timtower pointed out, your problem is that your two classes extend your main class, and when you create instances of said classes, they count as new instances of the main class, which Bukkit does not allow. Just stop extending your main class and you should be fine.