Why can I access the private members of an enclosing class reference

问题

I have seen many questions about accessing private members of an enclosing class. However, my question is the opposite.

If I have (as an example), the following code:

public class A {

   private String outerString = "silly string";

   static class B {
      private final A someA = new A();      

      public void foo() {
         String b = someA.outerString ;
      }
   }
}

I'm wondering why this compiles? I would have expected an error by virtue of the way in which I am accessing the 'outerString' instance variable from class A (via someA.outerString). I know that an inner class can access the enclosing class members directly by an implicit 'this' reference. But here, class B is static, so the 'this' reference won't apply.

回答1:

B is a member of A and therefore has access to A's private fields and methods.
In this case, although B is static it is using an instance of A to access the field A.outerString.

回答2:

static methods of a class can access private members of the same class through the same class instance. This behavior is consistent for static classes as well.

static void b(A someA) {
    String b = someA.outerString;
}

回答3:

1. this only works with non-static member, thats right..... But you are not using this but instance of the Outer Class.

2. And you can very well access the Outer class private member from the (Top level) inner static class.

3. Outer to Inner and from Inner to Outer has the ability to access the private member of each other..only difference is that, non static inner class has implicit reference to the Outer class, and for static inner class you must access using the Instance.

来源：https://stackoverflow.com/questions/11635282/why-can-i-access-the-private-members-of-an-enclosing-class-reference

标签

java

static-members

nested-class