自定义集合（补充）

 * 1.如何让普通的类具备foreach功能

 * 2.本类是缓存类,提供添加,删除,清除,移除等方法来管理对象(你想存的东西)

 * 缓存:

 * 1.用户的一些设置

class CacheManager:IEnumerable

{

private ArrayList _AL = new ArrayList();

//索引器

public object this [int index] 

{

get{ 

if (index > _AL.Count - 1) {

throw new Exception ("越界!");

} else {

return _AL [index];

}

}

}

//add方法

public void Add(object obj){

_AL.Add (obj);

}

//清除方法

public void Clean(){

_AL.Clear ();

}

//在指定下标位置插入元素

public void Insert(object obj,int index){

_AL.Insert (index, obj);

}

//查找

public int Find(object obj){

return _AL.IndexOf (obj);

}

//按下标移除

public void RemoveAt(int index){

_AL.RemoveAt (index);

}

//直接移除

public void Remove(object obj){

if (_AL.Contains (obj)) {

int index = _AL.IndexOf (obj);

RemoveAt (index);

} else {

Console.WriteLine ("异常!数组内不存在该元素:{0}", obj);

}

}

//继承IEnumerable需要实现的方法

public IEnumerator GetEnumerator (){

return new MyEnumrator(_AL);

}

}

class MyEnumrator:IEnumerator

{

private ArrayList _al;

private int index;

//构造方法

public MyEnumrator(ArrayList al){

_al = al;

}

//返回当前对象

public object Current {

get{ 

return _al [index++];

}

}

//如果枚举遍历器成功推进到下一个元素,则返回ture

public bool MoveNext (){

if (index > _al.Count - 1) {

return false;

} else {

return true;

}

}

//重置

public void Reset (){

index = 0;

}

}

class MainClass

{

public static void Main (string[] args)

{

User u1 = new User ("马志龙", "3687"); 

User u2 = new User ("黄河", "4gsb"); 

CacheManager cm = new CacheManager ();

cm.Add (u1);

cm.Add (u2);

foreach (User user in cm) { 

Console.WriteLine ("用户编号:{0},用户姓名:{1}",user.Id,user.Name);

}

}

}

User类

public class User

{

private string name;

private string id;

public string Name

{

set{

this.name = value;

}

get{

return this.name;

}

}

public string Id

{

set{

this.id = value;

}

get{

return this.id;

}

}

public User(string name,string id){

this.id = id;

this.name = name;

}

}