Plugin Class

import java.util.ArrayList;
import java.util.logging.Logger;

import org.bukkit.Bukkit;
import org.bukkit.block.Sign;
import org.bukkit.plugin.PluginDescriptionFile;
import org.bukkit.plugin.java.JavaPlugin;

public class MyPlugin extends JavaPlugin {
	public static final Logger logger = Logger.getLogger("Minecraft");
	public ArrayList<Sign> signs = new ArrayList<Sign>();
	public int taskId = -1;

	@Override
	public void onDisable() {
		PluginDescriptionFile pdfFile = this.getDescription();
		/* Cancels all tasks from this plugin */
		Bukkit.getScheduler().cancelTasks(this);
		logger.info(pdfFile.getName() + " version " + pdfFile.getVersion() + " is now disabled.");
	}

	@Override
	public void onEnable() {
		PluginDescriptionFile pdfFile = this.getDescription();
		/* Schedule your task in your onEnable()
		 *
		 * You can set it to an integer if you want to cancel individual tasks with
		 * Bukkit.getScheduler().cancelTask(taskId);
		 */
		taskId = Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(this, new RepeatingTask(this), 0, 1200);
		logger.info(pdfFile.getName() + " version " + pdfFile.getVersion() + " is now enabled.");
	}
}