Java与.net的区别delegate和event

There is no delegate concept in Java

The right-side C# program may be mimiced

with reflection technology.

在Java中没有delegate的概念，而C#中delegate使用的是类似Java中反射的工具。

import java.lang.reflect.*;

import java.io.*;

public class Test

{

    public static void main(String[] args) throws Exception

    {

        String[] list= {"to","be","or","not","to","be"};

        Method m1 = Test.class.getMethod("toConsole",new Class[] {String.class});

        Display(m1, list);

        Method m2 = Test.class.getMethod("toFile",new Class[] {String.class});

        Display (m2, list);

    }

    public static void toConsole (String str)

    {

        System.out.print(str+" ");

    }

    public static void toFile (String s)

    {

        File f = new File("delegate.txt");

        try{

            PrintWriter fileOut =

               new PrintWriter(new FileOutputStream(f));

            fileOut.write(s);

            fileOut.flush();

            fileOut.close();

        }catch(IOException ioe) {}

    }

    public static void display(Method m, String[] list)

    {

        for(int k = 0; k < list.length; k++) {

            try {

                Object[] args = {new String(list[k])};

                m.invoke(null, args);

            }catch(Exception e) {}

        }

    }

}

Delegate是引用类型允许间接访问方法。以下是简单和多维的委托Delegate

Delegates are reference types which allow

indirect calls to methods. There are single and multicast

delegates.

============================================

 using System;

 using System.IO;

 public class DelegateTest

 {

     public delegate void Print (String s);

     public static void Main()

     {

         Print s = new Print (toConsole);

         Print v = new Print (toFile);

         Display (s);

         Display (v);

     }

     public static void toConsole (String str)

     {

         Console.WriteLine(str);

     }

     public static void toFile (String s)

     {

         File f = new File("delegate.txt");

         StreamWriter fileOut = f.CreateText();

         fileOut.WriteLine(s);

         fileOut.Flush();

         fileOut.Close();

     }

     public static void Display(Print pMethod)

     {

         pMethod("This should be displayed in the console");

     }

 }

 A delegate instance encapsulates one or more methods,

 each of which is referred to as a callable entity.

 To add or reduce a list of calls

 by using operators += or -=.

 for example

 Print p = s + v;

 s += v;

对比可以得出的概念是：Java中没有这个Delegate的概念，但是通过反射的方法可以实现，C#却可以通过直接使用Delegate用来实现函数方法的间接调用。

巴特西

Java与.net的区别delegate和event

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