Command on NameTag

Hi!
I made a command and I want to solve it if you type it then the name of the tab is red and if you type it again then it will not be red, how can it be resolved? How to add code?

My Command Code:

Code:

    private ArrayList<String> Duty = new ArrayList<>();

    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args) {
        String command = cmd.getName();

        if (sender instanceof Player) {

            Player player = (Player) sender;
           
            if (command.equalsIgnoreCase("aduty")) {
                if (player.hasPermission("risegaming.admin.duty") || player.isOp()) {
                   
                    if(!Duty.contains(player.getName())) {
                        player.sendMessage(ChatColor.BLACK + "[" + ChatColor.RED + "AdminSystem" + ChatColor.BLACK + "]" + ChatColor.GREEN + "Sikeresen admin szolgálatba léptél!");
                        player.playSound(player.getLocation(), Sound.ENTITY_PLAYER_LEVELUP, 1, Integer.MAX_VALUE);
                        player.setAllowFlight(true);
                        player.setFlying(true);
                    } else {
                        player.sendMessage(ChatColor.BLACK + "[" + ChatColor.RED + "AdminSystem" + ChatColor.BLACK + "]" + ChatColor.GREEN + "Sikeresen kiléptél az admin szolgálatból!");
                        player.setAllowFlight(false);
                        player.setFlying(false);

                        Duty.remove(player.getName());
                    }
                }
                else {
                    player.sendMessage("Nincs jogod hozzá");
                    player.playSound(player.getLocation(), Sound.ENTITY_ZOMBIE_PIG_ANGRY, 1, Integer.MAX_VALUE);
                }
            }
        }
        return false;
    }

}

 

@ItsBlockFighter

1. You forgot to add the player to Duty if they are not in it.
2. Duty should be lower case. Variable names should start with a lowercase letter.
3. You only use command once. Remove it and replace the reference to it with cmd.getName
4. Main problem: If the player is in duty, have the chat message contain red.

 

?

 

@ItsBlockFighter
Which point confusing you?

 

Pretty sure he wants the name on top of the player red.