AbstractObservable.java

/*******************************************************************************
 * Copyright (c) 2004, 2013 Steve Flasby
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * <ul>
 *     <li>Redistributions of source code must retain the above copyright notice,
 *         this list of conditions and the following disclaimer.</li>
 *     <li>Redistributions in binary form must reproduce the above copyright notice,
 *         this list of conditions and the following disclaimer in the documentation
 *         and/or other materials provided with the distribution.</li>
 * </ul>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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package org.flasby.util;

import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


public class AbstractObservable implements Observable {
	private List<Observer> observers = new LinkedList<Observer>();
	private Lock observersLock = new ReentrantLock();
	
	@Override
	public void addObserver(Observer observer) {
		observersLock.lock();
		try {
			if(!observers.contains(observer)) {
				observers.add(observer);
			}
		} finally {
			observersLock.unlock();
		}
	}
	@Override
	public boolean removeObserver(Observer observer) {
		observersLock.lock();
		try {
			return observers.remove(observer);
		} finally {
			observersLock.unlock();
		}
	}

	public void notifyObservers() {
		observersLock.lock();
		Observer[] copy;
		try {
			copy = Arrays.newArray(observers.size(), Observer.class); 
			copy = observers.toArray(copy);
		} finally {
			observersLock.unlock();
		}

		for(Observer observer: copy) {
			observer.update(this);
		}
	}
	
	public void notifyObservers(Object object) {
		observersLock.lock();
		Observer[] copy;
		try {
			copy = Arrays.newArray(observers.size(), Observer.class); 
			copy = observers.toArray(copy);
		} finally {
			observersLock.unlock();
		}

		for(Observer observer: copy) {
			observer.update(this, object);
		}
	}
}