Vanish.java

package me.pogostick29.vanish;

import java.util.ArrayList;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.plugin.java.JavaPlugin;

public class Vanish extends JavaPlugin implements Listener {

    public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
    }

    private ArrayList<Player> vanished = new ArrayList<Player>();

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

        if (!(sender instanceof Player)) {
            sender.sendMessage(ChatColor.RED + "You cannot vanish!");
            return true;
        }

        Player p = (Player) sender;

        if (cmd.getName().equalsIgnoreCase("vanish")) {
            // Check perms

            if (!vanished.contains(p)) {
                for (Player pl : Bukkit.getServer().getOnlinePlayers()) {
                    pl.hidePlayer(p);
                }
                vanished.add(p);
                p.sendMessage(ChatColor.GREEN + "You have been vanished!");
                return true;
            }
            else {
                for (Player pl : Bukkit.getServer().getOnlinePlayers()) {
                    pl.showPlayer(p);
                }
                vanished.remove(p);
                p.sendMessage(ChatColor.GREEN + "You have been unvanished!");
                return true;
            }
        }
        return true;
    }

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent e) {
        for (Player p : vanished) {
            e.getPlayer().hidePlayer(p);
        }
    }

    @EventHandler
    public void onPlayerLeave(PlayerQuitEvent e) {
        vanished.remove(e.getPlayer());
    }
}