如何覆盖C＃中继承的类属性？ [英] How to override an inherited class property in C#?

问题描述

我学习了如何继承方法，通过向基类中的方法添加 virtual ，在新类中添加 override 类。

  class bird 
 {
 private virtual string fly =我可以！; 
 public string CanI（）{return fly; } 
} 
 
 class penguin：bird 
 {
 private override string fly =不，我不能！ 
} 
  

这会弹出一个错误，说修饰符 / code> / 重写不应在此使用。

解决方案

fly 不是属性，它是一个字段。字段不可覆盖。您可以这样做：

  class bird {
 protected virtual string Fly {
 get {
 return是的，我可以！ 
} 
} 
 public string CanI（）{return Fly; } 
} 
 
 class penguin：bird {
 protected override string Fly {
 get {
 return不，我不能！ 
} 
} 
} 
  

请注意， $

将会做这样的事情：

  abstract class Bird {
 public abstract bool CanFly {get; } 
 public string SayCanFly（）{
 if（CanFly）{
 return是的，我可以！ 
} 
 else {
 return不，我不能！ 
} 
} 
} 
 
 class Penguin：Bird {
 public override bool CanFly {
 get {
 return false; 
} 
} 
} 
 
 class Eagle：Bird {
 public override bool CanFly {
 get {
 return true; 
} 
} 
} 
  

I learned how to inherit methods by adding virtual to the method in the base class and override in the new class. But what do I do to inherit properties?

class bird
{
    private virtual string fly = "Yes, I can!";
    public string CanI() { return fly ; }
}

class penguin : bird
{
    private override string fly = "No, I can't!";
}

This pops an error, saying that modifiers virtual/override should not be used here.

解决方案

fly is not a property, it is a field. Fields are not overrideable. You can do this:

class bird {
    protected virtual string Fly {
        get {
            return "Yes, I can!";
        }
    }
    public string CanI() { return Fly; }
}

class penguin : bird {
    protected override string Fly {
        get {
            return "No, I can't!"; 
        }
    }
}

Note that I had to mark fly as protected.

But even better, I would do something like this:

abstract class Bird {
    public abstract bool CanFly { get; }
    public string SayCanFly() {
        if(CanFly) {
            return "Yes, I can!";
        }
        else {
            return "No, I can't!";
        }
    }
}

class Penguin : Bird {
    public override bool CanFly {
        get {
            return false;
        }
    }
}

class Eagle : Bird {
    public override bool CanFly {
        get {
            return true;
        }
    }
}

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