GMC

 public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {

        if (cmd.getName().equalsIgnoreCase("gms") && sender instanceof Player) {

            Player player = (Player) sender;

            player.setGameMode(GameMode.SURVIVAL);
            player.sendRawMessage("Gamemode changed to survival.");
            player.sendTitle( "Gamemode Changed." , "SURVIVAL" , 10 , 80 , 30 );

            return true;
        }

        else if (cmd.getName().equalsIgnoreCase("gmc") && sender instanceof Player) {

            Player player = (Player) sender;

            player.setGameMode(GameMode.CREATIVE);
            player.sendRawMessage("Gamemode changed to creative.");
            player.sendTitle( "", "", 10, 70, 20);


            return true;

            }

        return false;

        }