Bukkit - Using static variables causing problems

问题

So I've got this plugin I'm working on, I'll explain the feature so that you get an idea of what it's suppose to do:
-/showcps : tells the sender whenever the specified player left/right clicks

So, let's say there are two players, Bob and Billy on a server running this plugin; Bob does the command /showcps Billy and sees whenever Billy clicks. Then Billy types the command /showcps Bob, and now Billy sees when Bob clicks. The problem is that Bob can no longer see when Billy is clicking.

That's my problem. I think I know why it happens, but I'm not sure how to fix it. I used global variables to be able to use them interchangeably between the click listener and command executor classes.

Here's the code for the listeners:

@
EventHandler
public void leftClick(PlayerInteractEvent event) {
  Player player = event.getPlayer();

  if (event.getAction().equals(Action.LEFT_CLICK_AIR) | event.getAction().equals(Action.LEFT_CLICK_BLOCK)) {
    if (player.equals(ClickViewToggle.targetPlayer)) {
      ClickViewToggle.recivingPlayer.sendMessage(
        ChatColor.LIGHT_PURPLE + player.getName() + ChatColor.DARK_PURPLE + " left clicked.");
    }
  }
}

@
EventHandler
public void rightClick(PlayerInteractEvent event) {
  Player player = event.getPlayer();

  if (event.getAction().equals(Action.RIGHT_CLICK_AIR) | event.getAction().equals(Action.RIGHT_CLICK_BLOCK)) {
    if (player.equals(ClickViewToggle.targetPlayer)) {
      ClickViewToggle.recivingPlayer.sendMessage(
        ChatColor.LIGHT_PURPLE + player.getName() + ChatColor.DARK_PURPLE + " right clicked.");
    }
  }
}

Here is the code for the command executor:

public static Player targetPlayer = null;
public static Player recivingPlayer;

public boolean onCommand(CommandSender sender, Command command, String cmd, String[] args) {
  recivingPlayer = (Player) sender;
  if (args[0].isEmpty()) {
    if (sender instanceof Player) {
      sender.sendMessage(ChatColor.DARK_PURPLE + "You will now be able to see your clicks.");
      targetPlayer = (Player) sender;
      return false;
    } else {
      sender.sendMessage(ChatColor.DARK_PURPLE + "You must specify a player.");
      return false;
    }
  } else {
    boolean playerFound = false;
    for (Player player: Bukkit.getServer().getOnlinePlayers()) {
      if (player.getName().equalsIgnoreCase(args[0])) {
        sender.sendMessage(ChatColor.DARK_PURPLE + "You are now seeing " + ChatColor.LIGHT_PURPLE + player.getName() + ChatColor.DARK_PURPLE + "\'s clicks.");
        targetPlayer = player;
        playerFound = true;
        break;
      }
    }
    if (!playerFound) {
      sender.sendMessage(ChatColor.DARK_PURPLE + "Couldn't find " + ChatColor.LIGHT_PURPLE + args[0] + ChatColor.DARK_PURPLE + ".");
      targetPlayer = null;
    }
    return false;
  }
}

As you can see, receivingPlayer and targetPlayer are used between the two classes, but I feel like that's the reason that they both can't watch different clicks at the same time.

How can I fix this?

回答1:

I'd advise you to learn java before diving into Bukkit, because this code has serious problems.

Your problem occurs, because you have 1 variable to store the receiveng player and the sending player. This way, if you change it, then the old receiving player won't get any new messages. Use a hashmap with the sending player's UUID as key and the receiving player's UUID as value, then when a player is in the map, send a message to his corresponding receiver.

The other problems in yoir code:

Don't abuse static, it's a bad practice, use getters and setters.

Compare enums with == instead of .equal

You should have only 1 eventhandler for an event type in your plugin.

Never store full player objects, they cab cause a memory leak, if you're not careful enough.

args[0].isEmpty() only checks, if args[0] equals to an emoty string, if the player doesn't specify an argument, then this will throw an error.

These are the same kind of problems we at the http://bukkit.org forums encounter 90% of the time. Use that forum for Bukkit based questions, people can help more there.

来源：https://stackoverflow.com/questions/37871036/bukkit-using-static-variables-causing-problems

标签

java

bukkit