How to use

getId

method

in

cn.nukkit.item.Item

@Override
public int getFreeSlots(QueuedPlayer player) {
  Player player1 = getPlayer(player);
  if (player1 != null) {
    int free = 0;
    for (int i = 0; i < player1.getInventory().getSize(); i++) {
      if (player1.getInventory().getItem(i).getId() == 0) {
        free++;
      }
    }
    return free;
  }
  return -1;
}

  public boolean execute(CommandSender sender, String label, String[] args) {
    if (!this.testPermission(sender)) {
      return false;
    }
    if (!this.testIngame(sender)) {
      return false;
    }
    if (args.length > 1) {
      this.sendUsage(sender);
      return false;
    }
    Item item = ((Player) sender).getInventory().getItemInHand();
    String message = api.isRepairable(item) ? Language.translate("commands.itemdb.damage", String.valueOf(item.getDamage())) : Language.translate("commands.itemdb.meta", String.valueOf(item.getDamage()));
    if (args.length == 1) {
      switch (args[0]) {
        case "name":
          message = Language.translate("commands.itemdb.name", item.getName());
          break;
        case "id":
          message = Language.translate("commands.itemdb.id", String.valueOf(item.getId()));
          break;
      }
    }
    sender.sendMessage(message);
    return true;
  }
}

  public boolean execute(CommandSender sender, String label, String[] args) {
    if (!this.testPermission(sender)) {
      return false;
    }
    if (!this.testIngame(sender)) {
      return false;
    }
    if (args.length != 0) {
      this.sendUsage(sender);
      return false;
    }
    Player player = (Player) sender;
    if (player.isCreative() || player.isSpectator()) {
      sender.sendMessage(TextFormat.RED + Language.translate("commands.more.notavalible"));
      return false;
    }
    Item item = player.getInventory().getItemInHand();
    if (item.getId() == Item.AIR) {
      sender.sendMessage(TextFormat.RED + Language.translate("commands.more.air"));
      return false;
    }
    item.setCount(item.getMaxStackSize());
    player.getInventory().setItemInHand(item);
    sender.sendMessage(Language.translate("commands.more.success"));
    return true;
  }
}