重写受保护的方法，然后尝试从超类调用它 [英] Override a protected method, and try to call it from the super class

问题描述

我的问题来自一个项目.因此，让我抽象一些无关的细节.

My question comes from a project. So let me abstract away a bit unrelated details.

我有一个JAVA公共类A，它具有两个受保护的静态方法foo()和bar(). foo()方法在其主体中调用bar().

I have a JAVA public class A that has two protected static methods, foo() and bar(). The method foo() calls bar() in its body.

public class A{
  protected static foo(){
     ...
     bar()
     ...
  }
  protected static bar(){print("A.bar()");}

} 

现在我还有一个扩展A的类B.在B中，我重写了bar()

Now I also have a class B extending A. In B, I override bar()

class B extends A{
  @Overrides
  static protected bar(){ print("A.bar() extended");

}

最后，我从B中的一个类调用foo()

Finally, I call foo() from a class in B

class B extends A{
  ...
  public static main(){foo()} 
}

我不明白两点 1.编译器(Eclipse)要求我删除@Override注释.为什么? 2.最终main()输出"A.bar()"，这意味着已解决的bar()目标属于A类，但我打算重写bar()并使用A的foo()来调用修改后的bar( ).我怎样才能做到这一点?

I cannot understand two points 1. The compiler (Eclipse) asks me to remove @Override annotation. Why? 2. Finally the main() outputs "A.bar()", which means the resolved bar() target is of class A, but I intended to override bar() and use the A's foo() to call the modified bar(). How can I do that?

您对此有何看法?

推荐答案

1. 您不能覆盖静态方法.
2. 由于每种方法都是静态的，因此它是静态引用的.您首先呼叫A.foo()，后者又呼叫A.bar().由于您没有实例，因此覆盖方法不起作用.

1. You cannot override static methods.
2. Since every method is static it refers to them statically. You first call A.foo() which in turn calls A.bar(). Since you don't have instances, overriding methods does not work.

您需要从代码中删除所有static，并在其主体中使用new B().foo().

You need to remove all the static from your code and use new B().foo() in your main.

考虑阅读此教程.

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