故事
????小美是小雪最好的朋友。有一天, 小美問小雪:“小雪，怎么你的手機短信這么多啊，是不是談戀愛了？”，小雪笑了一下，說：“還沒呢”，小雪停頓了一下，“可是喜歡我的男孩倒是很多，這些男孩都不錯，眼都快花了”。小美想了想：“跟我說說這些男孩子，我幫你選一個最優秀的”。

??????果然，小美開始給小雪策劃了一個鉆石王老五大調查(遍歷)：
??? 1) 年齡小于30大于35者出局；
??? 2) 身高低于180cm者出局；
??? 3) 無房者出局；
??? 4) 無車者出局；
??? 5) 年薪低于100萬者出局。

迭代器模式(ITerator)的解決方案
?????? 迭代器模式的意圖：通過順序遍歷或逆序遍歷等方式訪問集合對象(List)中的各元素子對象(object)。一般來說，一個集合對象擁有兩個職責：一是存儲一組元素子對象；二是遍歷集合中的各元素子對象。從依賴性來講，前者是集合對象的根本屬性；后者是可分離的變化點。

子對象接口如下：

namespace?XiaoXue
{
????public?interface?IBoy
????{
????????string?Name{get;}
????????int?GetAge();
????????int?GetHeight();
????????bool?HasHouse();
????????bool?HasCar();
????????bool?HasMillion();
????}
}

子對象具體類如下:

namespace?XiaoXue
{
????public?class?BoyA?:?IBoy
????{
????????private?string?_Name="張三";
????????public?string?Name
????????{
????????????get{?return?_Name;}
????????}
????????public?int?GetAge()
????????{
????????????return?25;
????????}
????????public?int?GetHeight()
????????{
????????????return?187;
????????}
????????public?bool?HasHouse()
????????{
????????????return?true;
????????}
????????public?bool?HasCar()
????????{
????????????return?false;
????????}
????????public?bool?HasMillion()
????????{
????????????return?false;
????????}
????}
???public?class?BoyB?:?IBoy
????{
????????private?string?_Name="李四";
????????public?string?Name
????????{
????????????get{?return?_Name;}
????????}
????????public?int?GetAge()
????????{
????????????return?32;
????????}
????????public?int?GetHeight()
????????{
????????????return?170;
????????}
????????public?bool?HasHouse()
????????{
????????????return?true;
????????}
????????public?bool?HasCar()
????????{
????????????return?true;
????????}
????????public?bool?HasMillion()
????????{
????????????return?true;
????????}
????}
}

迭代器接口如下：

namespace?XiaoXue
{
???????public?interface?IListIterator
???????{
???????????void?First();
???????????void?Last();
???????????bool?MovePrevous();
???????????bool?MoveNext();
???????????object?Current{get;}
???????}
}

迭代器如下：

namespace?XiaoXue
{
???????public?class?BoyList:IListIterator
???????{
???????????private?List<IBoy>?boys?=?null;//子對象列表
???????????private?int?index=-1;
???????????public?BoyList()
???????????{
???????????????boys?=?new?List<IBoy>();
???????????}
???????????//添加子對象
???????????public?void?AddBoy(IBoy?boy)
???????????{
???????????????boys.Add(boy);
???????????}
???????????public?void?RemoveBoy(IBoy?boy)
???????????{
???????????????boys.Remove(boy);
???????????????index--;
???????????}
???????????public?void?First()
???????????{
???????????????index=0;
???????????}
???????????public?void?Last()
???????????{
???????????????index=boys.Count;
???????????}
???????????public?bool?MovePrevious()
???????????{
???????????????index--;
???????????????return?index>-1;
???????????}
???????????public?bool?MoveNext()
???????????{
???????????????index++;
???????????????return?index<boys.Count;
???????????}
???????????public?object?Current
???????????{
???????????????get?{return?this.boys[index];}
???????????}
????}
}

調用代碼如下：

IListIterator?iterator=new?BoyList();
iterator.AddBoy(new?BoyA());
iterator.AddBoy(new?BoyB());
while?(iterator.MoveNext())
{
???????IBoy?boy=(IBoy)iterator.Current
???????if?(boy.GetAge()<30?||?boy.GetAge()>35)
???????{
???????????iterator.RemoveBoy(boy);
???????}
???????else?if?(boy.GetHeight()<180)
???????{
???????????iterator.RemoveBoy(boy);
???????}
???????else?if?(!boy.HasHouse())
???????{
???????????iterator.RemoveBoy(boy);
???????}
???????else?if?(!boy.HasCar())
???????{
???????????iterator.RemoveBoy(boy);
???????}
???????else?if?(!boy.HasMillion())
???????{
???????????iterator.RemoveBoy(boy);
???????}
???????else
???????{
??????????????Console.WriteLine(boy.Name);
???????}
}

哈哈， 好象沒有一個符合條件的，俗話說：“什么樣的馬配什么樣的鞍”。這樣的王老五只有到月球上去找吧！

轉載于:https://www.cnblogs.com/ruochen/archive/2007/12/20/1006772.html

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