C#中声明、调用和配置事件的演示源码

下面的内容是关于C#中声明、调用和配置事件的演示的内容，应该能对大伙有些好处。

using System;
namespace MyCollections
{
using System.Collections;

public delegate void ChangedEventHandler(object sender, EventArgs e);

public class ListWithChangedEvent: ArrayList
{
public event ChangedEventHandler Changed;

protected virtual void OnChanged(EventArgs e)
{
if (Changed != null)
Changed(this, e);
}

public override int Add(object value)
{
int i = base.Add(value);
OnChanged(EventArgs.Empty);
return i;
}

public override void Clear()
{
base.Clear();
OnChanged(EventArgs.Empty);
}

public override object this[int index]
{
set
{
base[index] = value;
OnChanged(EventArgs.Empty);
}
}
}
}

namespace TestEvents
{
using MyCollections;

class EventListener
{
private ListWithChangedEvent List;

public EventListener(ListWithChangedEvent list)
{
List = list;
List.Changed += new ChangedEventHandler(ListChanged);
}

private void ListChanged(object sender, EventArgs e)
{
Console.WriteLine("This is called when the event fires.");
}

public void Detach()
{
List.Changed -= new ChangedEventHandler(ListChanged);
List = null;
}
}

class Test
{
public static void Main()
{
ListWithChangedEvent list = new ListWithChangedEvent();

EventListener listener = new EventListener(list);

list.Add("item 1");
list.Clear();
listener.Detach();
}
}
}

代码片段2

using System;
namespace MyCollections
{
using System.Collections;

public class ListWithChangedEvent: ArrayList
{
public event EventHandler Changed;

protected virtual void OnChanged(EventArgs e)
{
if (Changed != null)
Changed(this,e);
}

public override int Add(object value)
{
int i = base.Add(value);
OnChanged(EventArgs.Empty);
return i;
}

public override void Clear()
{
base.Clear();
OnChanged(EventArgs.Empty);
}

public override object this[int index]
{
set
{
base[index] = value;
OnChanged(EventArgs.Empty);
}
}
}
}

namespace TestEvents
{
using MyCollections;

class EventListener
{
private ListWithChangedEvent List;

public EventListener(ListWithChangedEvent list)
{
List = list;
List.Changed += new EventHandler(ListChanged);
}

private void ListChanged(object sender, EventArgs e)
{
Console.WriteLine("This is called when the event fires.");
}

public void Detach()
{
List.Changed -= new EventHandler(ListChanged);
List = null;
}
}

class Test
{
public static void Main()
{
ListWithChangedEvent list = new ListWithChangedEvent();

EventListener listener = new EventListener(list);

list.Add("item 1");
list.Clear();
listener.Detach();
}
}
}