Bukkit

package com.MyFillMonitor;

import org.bukkit.Bukkit;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;
import org.bukkit.scheduler.BukkitTask;

import com.wimbli.WorldBorder.Events.WorldBorderFillStartEvent;
import com.wimbli.WorldBorder.WorldFillTask;


public final class FillMonitorPlugin extends JavaPlugin
{
	@Override
	public void onEnable()
	{
		getServer().getPluginManager().registerEvents(new FillListener(this), this);
	}
}


class FillListener implements Listener
{
	private final JavaPlugin plugin;
	private final int repeatTicks = 100;  // 100 ticks = 5 seconds

	public FillListener(JavaPlugin plugin)
	{
		this.plugin = plugin;
	}

	@EventHandler(priority = EventPriority.LOWEST)
	public void onFillStart(WorldBorderFillStartEvent event)
	{
		BukkitTask task = new FillMonitorTask(event.getFillTask()).runTaskTimer(this.plugin, 1, repeatTicks);
	}
}



class FillMonitorTask extends BukkitRunnable
{
	private final WorldFillTask fillTask;

	public FillMonitorTask(WorldFillTask task)
	{
		this.fillTask = task;
	}

	@Override
	public void run()
	{
		if (fillTask == null || !fillTask.valid())
		{
			Bukkit.getServer().broadcastMessage("World Fill has ended!");
			this.cancel();
			return;
		}

		Bukkit.getServer().broadcastMessage("World Fill is at " + String.format("%.2f", fillTask.getPercentageCompleted()) + "%");
	}
}