Iterator(迭代器模式)--（超市管理者）

这个Iterator就是收银台干的活。

 

package patterns.actions.iterator;



public interface IteratorList {



	boolean isEmpty();//是否还有[hasNext()]

	

	Object nextMerchandise();//merchandise:商品

 

}

 

package patterns.actions.iterator;



/**

 * 收银台清点商品

 * @author one

 *

 */

public class IteratorCheck implements IteratorList {

	private Supermarket shop;

	

	private int total=0;

	

	private int current=0;

	

	IteratorCheck(Supermarket shop){

		this.shop=shop;

		this.total=shop.size();

		this.current=0;

	}



	@Override

	public boolean isEmpty() {

		return this.current<this.total;

	}



	@Override

	public Object nextMerchandise() {

		if(this.current<this.total)

			return this.shop.take(this.current++);

		return null;

	}

 

}

 

package patterns.actions.iterator;



/**

 * 购物的基本要素

 * @author one

 *

 */

public interface Shopping {



	public void buy(Object obj);//买新的产品[add]

	

	public IteratorList iteratorList();//结账[iterator]

	

}

 

package patterns.actions.iterator;



import java.util.ArrayList;

import java.util.List;



/**

 * 超市提供具体的购物环境

 * 

 * @author one

 * 

 */

public class Supermarket implements Shopping {

	private List cart = new ArrayList();// 购物车作为容器



	@Override

	public void buy(Object obj) {

		cart.add(obj);// 将商品放到购物车



	}



	@Override

	public IteratorList iteratorList() {

		return new IteratorCheck(this);

	}



	public int size() {

		return this.cart.size();

	}



	public Object take(int current) {

		if(current<this.cart.size())

			return this.cart.get(current);

		return null ;

	}

}

 

package patterns.actions.iterator;



public class Client {



	/**

	 * @param args

	 */

	public static void main(String[] args) {

		Shopping cart = new Supermarket();

		cart.buy("可乐");

		cart.buy("果汁");

		cart.buy("酸梅");



		IteratorList check = cart.iteratorList();

		while (check.isEmpty()) {

			System.out.println(check.nextMerchandise());

		}



	}



}

输出结果：

 

 

可乐

果汁

酸梅