How to define and use custom events in c#-C#.Net Tutorial-php.cn

How to define and use custom events in c#

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Release： 2020-10-12 17:35:36

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C# How to define and use custom events in the program: first define the event in the class; then define the parameters of the event; then trigger the event in TestClass; and finally use the event.

How to define and use custom events in c#

C#The steps to define and use custom events in the program are: first define the event in the class, and then define the parameters of the event in TestClass Trigger the event and finally use the event

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C# Defining and using custom events in the program can be divided into the following Several steps:

Step 1: Define the event in the class

using System;
public class TestClass
{
    //....
    public event EventHandler TestEvent
}

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Step 2: Define the event parameters

Note : Event parameter class TestEventArgs inherits from System.EventArgs

using System;
public class TestEventArgs : EventArgs
{
    public TestEventArgs() : base() { }
 
    public string Message { get; set; }
}

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Step 3: Raise event in TestClass

public class TestClass
{
    // 这个方法引发事件
    public void RaiseTestEvent(string message)
    {
        if (TestEvent == null) return;
        TestEvent(this, new TestEventArgs { Message = message });
    }
    public event EventHandler TestEvent; 
}

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Step 4: Use event

class Program
{
    static void Main(string[] args)
    {
 
        TestClass tc = new TestClass();
        // 挂接事件处理方法
        tc.TestEvent += Tc_TestEvent;
         
        Console.WriteLine("按任意键引发事件");
        Console.ReadKey();        
        // 引发事件
        tc.RaiseTestEvent("通过事件参数传递的字符串");
         
        Console.WriteLine("按任意键退出");
        Console.ReadKey();
    }
    private static void Tc_TestEvent(object sender, EventArgs e)
    {
        // 将事件参数强制转换为TestEventArgs
        TestEventArgs te = (TestEventArgs)e;
        // 显示事件参数中的Message
        Console.WriteLine(te.Message);
    }
}

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The complete program is as follows

using System;
public class TestClass
{
    public void RaiseTestEvent(string message)
    {
        if (TestEvent == null) return;
        TestEvent(this, new TestEventArgs { Message = message });
    }
 
    public event EventHandler TestEvent; 
}
public class TestEventArgs : EventArgs
{
    public TestEventArgs() : base() { }
 
    public string Message { get; set; }
}
class Program
{
    static void Main(string[] args)
    {
 
        TestClass tc = new TestClass();
        tc.TestEvent += Tc_TestEvent;
        Console.WriteLine("按任意键引发事件");
        Console.ReadKey();
        tc.RaiseTestEvent("通过事件参数传递的字符串");
        Console.WriteLine("按任意键退出");
        Console.ReadKey();
    }
    private static void Tc_TestEvent(object sender, EventArgs e)
    {
        TestEventArgs te = (TestEventArgs)e;
        Console.WriteLine(te.Message);
    }
}

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