NotificationCenter.java

package Notification;

import java.util.ArrayList;
import java.util.Hashtable;

public class NotificationCenter {
	private static NotificationCenter _instance = null;

	private Hashtable<NotificationMessageT, ArrayList<ILDrawSubscriber>> subscriberList;

	private NotificationCenter() {
		subscriberList = new Hashtable<NotificationMessageT, ArrayList<ILDrawSubscriber>>();
	}

	public static synchronized NotificationCenter getInstance() {
		if (_instance == null)
			_instance = new NotificationCenter();

		return _instance;
	}

	public void addSubscriber(ILDrawSubscriber subscriber,
			NotificationMessageT notificationMessageType) {
		synchronized (this) {
			if (subscriberList.containsKey(notificationMessageType) == false) {
				subscriberList.put(notificationMessageType,
						new ArrayList<ILDrawSubscriber>());
			}
			ArrayList<ILDrawSubscriber> temp = subscriberList
					.get(notificationMessageType);
			if (temp.contains(subscriber) == false)
				temp.add(subscriber);
		}
	}

	public void removeSubscriber(ILDrawSubscriber subscriber,
			NotificationMessageT notificationMessageType) {
		synchronized (this) {

			if (subscriberList.containsKey(notificationMessageType) == false)
				return;
			ArrayList<ILDrawSubscriber> temp = subscriberList
					.get(notificationMessageType);
			if (temp.contains(subscriber) == true)
				temp.remove(subscriber);
		}
	}

	public void postNotification(NotificationMessageT notificationType, INotificationMessage message) {
//		System.out.println(notificationType);
		if (subscriberList.containsKey(notificationType) == false)
			return;
		ArrayList<ILDrawSubscriber> temp = subscriberList.get(notificationType);
		for (ILDrawSubscriber subc : temp)
			subc.receiveNotification(notificationType, message);
	}
	
	public void postNotification(NotificationMessageT notificationType) {
		postNotification(notificationType, null);
	}
}