ArrayList简单实现代码，欢迎大家指点
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace MyArrayList_hjf
{
class MyArrayList : IEnumerable
{
object[] objarr = new object[0];
int count;
public MyArrayList()
{
}
public MyArrayList(int capacity)
{
this.Capacity = capacity;
}
/// <summary>
/// 索引器
/// </summary>
/// <param name="index">索引值</param>
/// <returns></returns>
public object this[int index]
{
get
{
if (index > count)
{
throw new Exception("索引超出范围");
}
else
{
if (index > count)
{
throw new Exception("索引超出范围");
}
else
{
return objarr[index];
}
}
}
set
{
if (index < count)
{
objarr[index] = value;
}
else
{
throw new Exception("索引超出范围");
}
}
}
/// <summary>
/// 获取数组的长度
/// </summary>
public int Count
{
get
{
return count;
}
}
/// <summary>
/// 获取或设置数组的容量
/// </summary>
public int Capacity
{
get
{
return objarr.Length;
}
set
{
if (value < count)
{
throw new Exception("容量小于元素个数");
}
else
{
object[] temparr = new object[value];
for (int i = 0; i < count; i++)
{
temparr[i] = objarr[i];
}
objarr = temparr;
}
}
}
/// <summary>
/// 添加数组元素
/// </summary>
/// <param name="value">要添加的值</param>
/// <returns></returns>
public int Add(object value)
{
if (objarr.Length == 0)
{
objarr = new object[4];
objarr[0] = value;
count++;
return 0;
}
else
{
if (Count < objarr.Length)
{
objarr[count] = value;
count++;
return count - 1;
}
else
{
object[] tempObj = new object[objarr.Length * 2];
for (int i = 0; i < count; i++)
{
tempObj[i] = objarr[i];
}
tempObj[count] = value;
count++;
objarr = tempObj;
return count - 1;
}
}
}
/// <summary>
/// 移除指定项的第一个匹配元素
/// </summary>
/// <param name="obj">要移除的对象</param>
public void Remove(object obj)
{
int num = -1;
for (int i = 0; i < count; i++)
{
if (objarr[i].Equals(obj))
{
num = i;
break;
}
}
if (num != -1)
{
for (int j = num; j < count; j++)
{
objarr[j] = objarr[j + 1];
}
count--;
}
}
/// <summary>
/// 用于foreach循环
/// </summary>
/// <returns></returns>
public IEnumerator GetEnumerator()
{
for (int i = 0; i < count; i++)
{
yield return objarr[i];
}
}
/// <summary>
/// 移除数组中所有元素
/// </summary>
public void Clear()
{
for (int i = 0; i < count; i++)
{
objarr[i] = null;
}
count = 0;
}
/// <summary>
/// 把数组中所有元素反转
/// </summary>
public void Reverse()
{
object[] tempArr = new object[count];
int num = 0;
for (int i = count - 1; i >= 0; i--)
{
tempArr[num] = objarr[i];
num++;
}
objarr = tempArr;
}
/// <summary>
/// 确定某元素是否存在与该数组中
/// </summary>
/// <param name="item">要在数组中查找的对象，该对象可以为null</param>
/// <returns></returns>
public bool Contains(object item)
{
bool mark = false;
foreach (object o in objarr)
{
if (o.Equals(item))
{
mark = true;
break;
}
}
return mark;
}
/// <summary>
/// 移除指定索引处的元素
/// </summary>
/// <param name="index">index:要移除的元素的从0开始的索引</param>
public void RemoveAt(int index)
{
if (index < 0 || index > count)
{
throw new Exception("索引超出范围，必须为非负值并小于集合大小。");
}
else
{
for (int i = index; i < count; i++)
{
objarr[i] = objarr[i + 1];
}
count--;
}
}
/// <summary>
/// 将元素插入到指定的索引处
/// </summary>
/// <param name="index">index:从0开始的索引，应该在该位置插入value</param>
/// <param name="value">要插入的值，该值可以为null</param>
public void Insert(int index, object value)
{
ArrayList al = new ArrayList();
if (index < 0 || index > count)
{
throw new Exception("插入索引已超出范围，必须为非负值，并且小于或等于集合大小。");
}
else
{
//如果数组长度小于集合容量
if (count < Capacity)
{
if (index < count)
{
for (int i = count - 1; i >= index; i--)
{
objarr[i + 1] = objarr[i];
}
objarr[index] = value;
count++;
}
else if (index == count)
{
objarr[index] = value;
count++;
}
}
else if (count == Capacity)
{
object[] tempArr = new object[objarr.Length * 2];
for (int j = 0; j < count;j++ )
{
tempArr[j]=objarr[j];
}
objarr = tempArr;
if (index < count)
{
for (int i = count - 1; i >= index; i--)
{
objarr[i + 1] = objarr[i];
}
objarr[index] = value;
count++;
}
else if (index == count)
{
objarr[index] = value;
count++;
}
}
}
}
}
}
