???????? 顧名思義，迭代器模式就是順序訪問聚集中的對(duì)象，一般來(lái)說(shuō)，集合中非常常見，如果對(duì)集合類比較熟悉的話，理解本模式會(huì)十分輕松。這句話包含兩層意思：一是需要遍歷的對(duì)象，即聚集對(duì)象，二是迭代器對(duì)象，用于對(duì)聚集對(duì)象進(jìn)行遍歷訪問。我們看下關(guān)系圖：

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????

public interface Collection { public Iterator iterator(); /*取得集合元素*/ public Object get(int i); /*取得集合大小*/ public int size(); }

?

public?interface?Iterator?{??

????//前移??

????public?Object?previous();??

??????

????//后移??

????public?Object?next();??

????public?boolean?hasNext();??

??????

????//取得第一個(gè)元素??

????public?Object?first();??

}??

?

public?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;??

????}??

}??

?

public?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);??

????}??

??

}??

?

?

public?class?Test?{??

??

????public?static?void?main(String[]?args)?{??

????????Collection?collection?=?new?MyCollection();??

????????Iterator?it?=?collection.iterator();??

??????????

????????while(it.hasNext()){??

????????????System.out.println(it.next());??

????????}??

????}??

}??

?

?

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