有人请解释一下 [英] some one please explain this

问题描述

朋友，

任何人都可以给我这个程序的解释吗?

在Java中的输出:

Hi Friends,

Can anyone give me a explnation for this program??

in Java the output :

Hi From derived

在C#中的输出:

in C# the Output :

Hi From base

为什么两种语言都会混淆概念?


但是用两种语言-对象类型是派生类

Why oops concept diffrent in both langauges ?


but in both language - the object type is derived class

class Program
 {
     static void Main(string[] args)
     {
         MyClass A= new MyClass1();
         A.h1();

         System.Type type = A.GetType();
         Console.WriteLine(type.ToString());
         
     }
 }
 public class MyClass
 {
     
     public void h1()
     {
         Console.WriteLine("Hi From base");
     }

 }
public class MyClass1 :MyClass
 {
     public void h1()
     {
         Console.WriteLine("Hi From derived");
     }
     
 }

推荐答案

如果要在派生类中重写该方法，则需要在基类中将其标记为虚方法.

If you want the method to be overridden in a derived class you need to mark it as virtual in the base.

public class MyClass
 {

     public virtual void h1()
     {
         Console.WriteLine("Hi From base");
     }

 }
public class MyClass1 :MyClass
 {
     public override void h1()
     {
         Console.WriteLine("Hi From derived");
     }

 }

有了它，您的MyClass A实例就只知道它包含的h1方法.

As you have it your instance of MyClass, A, only knows of the h1 method it contains.

请首先解决警告！每个警告都可能是一个问题.
现在您遇到了一个隐藏的问题.
我猜您在编译C#时发出了警告，对吧?

IIRC在Java中都是虚拟的，而在C#中只有这样声明的方法.
(不过，我不是Java程序员)


这是在Visual Studio 2010中针对C#的警告:

Fix the warnings first! Each warning might be a problem.
And you run now into a hiding issue.
I guess you had a warning while you did compile C#, right?

IIRC, in Java, all is virtual, while in C# only the so declared methods are.
(I''m not a Java programmer, though)


This is the warning you get for C# in Visual Studio 2010:

Warning 1 'ConsoleApplication1.MyClass1.h1()' hides inherited member 'ConsoleApplication1.MyClass.h1()'. Use the new keyword if hiding was intended.

但是我必须承认:在警告上按Visual Studio 2010中的F1以获取有关它的更多详细信息时，来自Microsoft的帮助文本简直就是废话.没有关于虚拟/覆盖的消息.没有给出最简单的解决方案:重命名隐藏成员，也没有给出有关虚拟/覆盖的任何信息...
我会说:没有人"想要隐藏成员-要求维护麻烦.
为什么有人会通过应用new关键字想要隐藏隐藏成员?
? [/EDIT]

But I have to admit: when pressing F1 in Visual Studio 2010 on that warning to get more details on it, the help text from Microsoft is crap. No word about virtual/override. The simplest solution is not given: rename the hiding member, nor any word about virtual/overriding is given...
I would say: "no one" ever wants to hide a memeber - calls for maintenance trouble.
Any example why one would want to hide a member by applying the new keyword?
[/EDIT]

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