Question Buggy Strings?

Hi, I am writing my 2. Plugin and I got a Mistake, wich I am not able to explain:
i wrote this to declare a new command:

Code:

    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args){
        if(cmd.getName().equalsIgnoreCase("challenge")){
            if(sender instanceof Player){
                Debug("the sender is a Player");
            }else{
                Debug("the sender is no Player");
                System.out.println("this command is only executable by players");
                return true;
            }
            Player p = (Player) sender;
            if(args.length < 2){
                p.sendMessage(ChatColor.RED+"too little Arguments");
                return true;
            }
            Debug("The Command "+cmd+" will be executed");
            Debug("The Arguments:  "+args[0]+args[1]);
            Debug("Command parts:Sender: "+sender.getName()+" Command:"+cmd.getName()+" label"+ label+" Argumente: "+args);
            if(args[0] != "invite"){
                Debug("the firs argument is not invite");
                Debug(args[0]+ " != invite");
            }
...
}

the debug() method is only:

Code:

public String Debug(String str){
        if(Debug==true){
            Bukkit.getConsoleSender().sendMessage(ChatColor.GREEN+"[Debug LuckyLobby] "+ChatColor.BLACK+str);
        }
        if(DebugChat==true){
            Player p = Bukkit.getPlayer("mrgum13");
            if(p != null){
                Bukkit.getPlayer("mrgum13").sendMessage(ChatColor.GREEN+"[Debug LuckyLobby] "+ChatColor.WHITE+str);
            }
        }
        return "";
    }

I loaded my plugin and executed: /challenge invite mrgum13
the argument 0 (args[0]) = invite
and if it isn´t invite it will say me that, but: (server log)

Code:

[21:52:06 INFO]: mrgum13 issued server command: /challenge invite mrgum13
[21:52:06 INFO]: [Debug LuckyLobby] Der Sender ist ein Spieler
[21:52:06 INFO]: [Debug LuckyLobby] The Command org.bukkit.command.PluginCommand(challenge, LuckyLobby v1.0) will be executed
[21:52:06 INFO]: [Debug LuckyLobby] the arguments: invitemrgum13
[21:52:06 INFO]: [Debug LuckyLobby] Command parts:Sender: mrgum13 Command:challenge labelchallenge Argumente: [Ljava.lang.String;@5b073e42
[21:52:06 INFO]: [Debug LuckyLobby] the 1. argument isn?t invite
[21:52:06 INFO]: [Debug LuckyLobby] invite != invite

Can me anyone say what is wrong
The plugin.yml is right, i tested it before this "mistake"
the log wrote: [21:52:06 INFO]: [Debug LuckyLobby] invite != invite
the first invite is the argument, the second a string!
I´m helpless please help me!

 

== compares the object in memory. Use .equals() as it compares value.