iterator (eleventh day)_volumenames.iterator() 便利-优快云博客

本文详细解释了迭代模式的概念，并通过Java代码展示了如何实现迭代器接口、聚合对象和具体迭代器，以及具体聚合对象的创建过程。

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* 迭代模式：提供一种方法顺序访问一个聚合对象中的各个元素，而又不需要暴漏该独享的内部表示
* Iterator：迭代器接口。定义访问和遍历元素的接口
* ConcreteIterator: 具体的迭代器的实现对象。实现对象聚合对象的遍历，并跟踪便利时的当前位置
* Aggregate: 聚合对象。定义创建相应迭代器对象的接口。
* ConcreteAggregate: 具体聚合对象。实现创建爱你相应的迭代器对象

public interface Iterator {
	public void first();
	
	public void next();
	
	public boolean isDone();
	
	public Object CurrentItem();
}

public abstract class Aggregate {
	public abstract Iterator createIterator();

}

public class ConcreteAggregate extends Aggregate{
	private String [] as = null;
	
	public ConcreteAggregate (String [] ss){
		this.as = ss;
	} 
 	public Iterator createIterator() {
 		return new ConcreteIterator(this);
	}
 	public Object get(int index){
 		Object retObj = null;
 		if(index < as.length){
 			retObj = as[index];
 		}
 		return retObj;
 	}
 	public int size(){
 		return this.as.length;
 	}

}

public class ConcreteIterator implements Iterator{
	private ConcreteAggregate aggregate;
	
	private int index = -1;
	
	public ConcreteIterator(ConcreteAggregate aggregate){
		this.aggregate = aggregate;
	}
	@Override
	public Object CurrentItem() {
 		return this.aggregate.get(index);
	}

	@Override
	public void first() {
 		index = 0;
	}

	@Override
	public boolean isDone() {
		if(index < this.aggregate.size()){
			return true;
		}
 		return false;
	}

	@Override
	public void next() {
 		if(index<this.aggregate.size()){
 			index  = index+1;
 		}
	}

}

public class Client {
	
	static String [] names = {"张三","李四","王五"};
	
public static void main(String[] args) {
	Aggregate aggregate = new ConcreteAggregate(names);
	Iterator it = aggregate.createIterator();
	it.first();
	while(it.isDone()){
		Object obj = it.CurrentItem();
		System.out.println(obj);
		it.next();
	}
	new ArrayList().iterator();
}

}