datasubject.java.svn-base

这个是我做j2ee培训时候自己整理和编写的设计模式的学习例子

package org.hyq.observer0;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

@SuppressWarnings("unchecked")
public class DataSubject implements Subject {
	private List dataList;
	private ArrayList observers = new ArrayList();

	/**
	 * default constructor
	 */
	public DataSubject() {
		dataList = new LinkedList();
		dataList.add("Benz");
		dataList.add("Audi");
		dataList.add("Bmw");
	}

	public void add(String carName) {
		dataList.add(carName);
		notifyObservers();
	}

	public Iterator iterator() {
		return dataList.iterator();
	}

	public String remove(int index) {
		if (index < dataList.size()) {
			String str = (String) dataList.remove(index);
			notifyObservers();
			return str;
		}
		return null;
	}

	public void addObserver(Observer o) {
		observers.add(o);
	}

	public void removeObserver(Observer o) {
		observers.remove(o);
	}

	public void notifyObservers() { // loop through and notify each observer
		Iterator i = observers.iterator();
		while (i.hasNext()) {
			Observer o = (Observer) i.next();
			o.update(this);
		}
	}
	public int getDataSize(){
		return dataList.size();
	}
}