路一步步走>> 设计模式十六：Iterator-迭代器

版权声明：本文为博主原创文章，未经博主允许不得转载。个人公众号：百草疯茂 https://blog.csdn.net/wang_pengyu/article/details/84891987

package com.test.DPs.XingWei.Iterator;

/**
 * 行为型：Iterator-迭代器		外观：作用面为 对象
 * 
 * 用途：提供一种方法顺序访问一个聚合对象中各个元素，而又不需要暴露该对象的内部表示。
 * 理解：一是需要遍历的对象，即聚集对象，
 *     二是迭代器对象，用于对聚集对象进行遍历访问
 */
interface Collection{
	Iterator iterator();
	Object get(int i);
	int size();
}
interface Iterator{
	Object previous();
	Object next();
	boolean hasNext();
	Object first();
}
class myCollection implements Collection{
	public String string[] = {"A","B","C","D","E"};
	@Override
	public Iterator iterator(){
		return new myIterator(this);
	}
    @Override  
    public Object get(int i) {  
        return string[i];  
    }  
    @Override  
    public int size() {  
        return string.length;  
    }  
}
class myIterator implements Iterator{
	private Collection collection;
	private int pos = 1;
	public myIterator(Collection collection){
		this.collection = collection;
	}
	@Override
	public Object previous(){
		if(pos>0){
			pos--;
		}
		return collection.get(pos);
	}
	@Override  
    public Object next() {  
        if(pos<collection.size()-1){  
            pos++;  
        }  
        return collection.get(pos);  
    }  
    @Override  
    public boolean hasNext() {  
        if(pos<collection.size()-1){  
            return true;  
        }else{  
            return false;  
        }  
    }  
    @Override  
    public Object first() {  
        pos = 0;  
        return collection.get(pos);  
    }  
}