Edwardia's little custom plugin

Edwardia.java

package com.github.jikoo.edwardia;

import java.util.HashMap;
import java.util.HashSet;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerBedEnterEvent;
import org.bukkit.event.player.PlayerBedLeaveEvent;
import org.bukkit.event.player.PlayerChangedWorldEvent;
import org.bukkit.event.player.PlayerQuitEvent;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.ShapelessRecipe;
import org.bukkit.plugin.java.JavaPlugin;

/**
 * Edwardia's custom plugin. Currently includes an adaptation of Sblock's SleepVote and a recipe for
 * clay blocks from gravel.
 * 
 * @author Jikoo
 */
public class Edwardia extends JavaPlugin implements Listener {

	private HashMap<String, HashSet<String>> votes;

	public void onEnable() {
		votes = new HashMap<String, HashSet<String>>();
		getServer().getPluginManager().registerEvents(this, this);
		ShapelessRecipe sr = new ShapelessRecipe(new ItemStack(Material.CLAY, 4));
		sr.addIngredient(8, Material.GRAVEL);
		sr.addIngredient(Material.WATER_BUCKET);
		Bukkit.addRecipe(sr);
	}

	public void onDisable() {
		votes.clear();
		votes = null;
	}

	@EventHandler(ignoreCancelled = true)
	public void onPlayerBedEnter(PlayerBedEnterEvent event) {
		addVote(event.getPlayer().getWorld(), event.getPlayer());
	}

	@EventHandler(ignoreCancelled = true)
	public void onPlayerBedLeave(PlayerBedLeaveEvent event) {
		removeVote(event.getPlayer().getWorld().getName(), event.getPlayer().getName());
	}

	@EventHandler(ignoreCancelled = true)
	public void onPlayerQuit(PlayerQuitEvent event) {
		removeVote(event.getPlayer().getWorld().getName(), event.getPlayer().getName());
	}

	@EventHandler(ignoreCancelled = true)
	public void onPlayerChangedWorld(PlayerChangedWorldEvent event) {
		removeVote(event.getPlayer().getWorld().getName(), event.getPlayer().getName());
	}

	public void addVote(World world, Player p) {
		if (!votes.containsKey(world.getName())) {
			votes.put(world.getName(), new HashSet<String>());
			resetVote(world);
		}
		if (votes.get(world.getName()).add(p.getName())) {
			updateVotes(world, p.getName());
		}
	}

	public void removeVote(String world, String player) {
		if (!votes.containsKey(world)) {
			return;
		}
		if (player != null) {
			votes.get(world).remove(player);
		}
	}

	public void updateVoteOnLeave(World world, String player) {
		removeVote(world.getName(), player);

		updateVotes(world, null);
	}

	public void updateVotes(World world, String player) {
		if (!votes.containsKey(world.getName())) {
			// No vote running in this world, nothing to update.
			return;
		}
		StringBuilder sb = new StringBuilder();
		int worldsize = world.getPlayers().size();
		if (player != null) {
			sb.append(ChatColor.GREEN).append(player).append(ChatColor.YELLOW).append(" has gone to bed. ");
		} else {
			// Size still reports as it would if player leaving was in the world. Rather than waste resources on a task, subtract 1.
			worldsize--;
		}
		int percent = worldsize < 1 ? 100 : (int) 100 * votes.get(world.getName()).size() / worldsize;
		sb.append(ChatColor.YELLOW).append(percent).append("% of players have slept.");
		if (percent >= 50) {
			sb.append('\n').append("Time to get up, a new day awaits!");
			world.setTime(0);
			world.setStorm(false);
			world.setWeatherDuration(world.getWeatherDuration() > 12000 ? world.getWeatherDuration() : 12000);
			Bukkit.getConsoleSender().sendMessage("[SleepVote] " + world.getName() + " set to morning!");
			votes.remove(world.getName());
		} else if (player == null) {
			// No spam on log out
			return;
		}
		String msg = sb.toString();
		for (Player p : world.getPlayers()) {
			p.sendMessage(msg);
		}
	}

	public void resetVote(final World world) {
		Bukkit.getScheduler().scheduleSyncDelayedTask(this, new Runnable() {

			@Override
			public void run() {
				votes.remove(world.getName());
			}
		}, 24001 - world.getTime());
	}
}