How to make message if player use the command witout args?

How to make message if player use the command witout args?
How to check will have args in entered command?

Code:

    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
        Player p = (Player) sender;
        Player g = Bukkit.getPlayerExact(args[0]);

 

If i use this code:

if(args.length == 0) - it's doesn't work i have error if you only /command

If i use this:

if(args.length =< 1) -I have error if enter only (/command) but if i enter (/command g) or (/command 6) evetring work.

I need if i enter (/command) i get message and retuen true

 

Code:

    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
        Player p = (Player) sender;
        Player g = Bukkit.getPlayerExact(args[0]);
        //if(args.hashCode() == 0){
        //    p.sendMessage(ChatColor.RED + "ERROR. Enter /command nick");
        //    return true;
        //}
        if (cmd.getName().equalsIgnoreCase("uplevel")) {
            if (getLevel(g) >= main.instance.getConfig().getInt("MaxLevel")) {
                p.sendMessage(ChatColor.YELLOW + "Player is MaxLevel!");

                return true;
            }
            main.instance.getConfig().getInt("levels." + getNextLevel(g) + ".blocks");
            levels.put(g.getName(), Integer.valueOf(getLevel(g) + 1));
            p.sendMessage(ChatColor.GREEN + "New level " + ChatColor.GOLD + levels.get(g.getName()));
            g.sendMessage(ChatColor.GREEN + "Игрок: " + p.getName() + " up your level  " + ChatColor.GOLD + levels.get(g.getName()));
            p.setMaxHealth((18 + getLevel(g) * 2));
            g.setLevel(levels.get(g.getName()));
            updateScoreboard(g);
            return true;
        }

 

ops , i'm so sorry, replace hashCode() on length

 

How to make this?