嵌套的内部 class 是否自动从 java 中的外部 class 的超类继承？

Question

Say I have an Outer class A and it's nested Inner Class B. A is subclass of C. Then is B also a subclass of C? Since B can access all private members of A and thus that(public and protected) of it's superclass, so I think B becomes a subclass of C.

Is my line of thinking right?

Any help is highly appreciated.

Answer 1

Here's what you seem to be describing:

class C {} 
class A extends C {
    static class B {}
}

Being a nested class in A does not make B a subclass of C . Access to members is not the defining characteristic of being a subclass.

Suppose you try to assign an object of type B to a variable of type C .

C c1 = new A(); // OK -- A is a subclass of C
C c2 = new A.B(); // Not OK

If B were a subclass of C , the latter would be a legal assignment. But it is not.

Answer 2

I don't think so. If you want B to extend C, you may explicitly say:

class C {}

class A extends C {

    static class B extends C {
        //Todo...
    }
}

The nested class B is just a (static) member of A just like any other member of it. You can access public and protected or even package access methods and variables of C within B because A has inherited those members from C. Since B is a nested class of A, You can access (static) members of A which can be inherited from other class or not.