什麼時候/爲什麼要使用EventHandler而不是常規事件？

Question

使用EventHandler並僅定義事件的功能是否存在差異？

Answer 1

這是兩個不同的東西

event聲明事件：

https://msdn.microsoft.com/en-us/library/8627sbea.aspx

EventHandler定義的事件將提高方法：

https://msdn.microsoft.com/en-us/library/system.eventhandler(v=vs.110).aspx

EventHandler<TEventArgs>是您的自定義EventArgs一個方便的包裝：

https://msdn.microsoft.com/en-us/library/db0etb8x(v=vs.110).aspx

不同的方式來訂閱事件

using System; 

namespace ConsoleApplication3 
{ 
    internal class Program 
    { 
     private static void Main(string[] args) 
     { 
      // using a method 
      MyEvent += Program_MyEvent; 

      // using EventHandler, possible but not mandatory 
      MyEvent += new EventHandler(Target); 

      // using lambda syntax 
      MyEvent += (sender, eventArgs) => { }; 

      // using delegate 
      MyEvent += delegate (object sender, EventArgs eventArgs) { }; 

      // using delegate, signature is optional actually 
      MyEvent += delegate { }; 
     } 

     private static void Target(object sender, EventArgs eventArgs) 
     { 
     } 

     private static void Program_MyEvent(object sender, EventArgs e) 
     { 
     } 

     public static event EventHandler MyEvent; 
    } 

}