另一个内部类的内部子类-根类有多少个引用？

Question

Suppose I have the structure

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

It seems that instances of C should have 2 references to the root class A : the first is inherited from B superclass, the second is own implicit inner class reference. My question: does JVM (HotSpot) optimize this case and keep only one reference to the root class?

Answer 1

I decompiled A.class and got this result which shows two references to A, one from B and one from C. But this actually means that C actually has two references - one is its own and the other is inherited from B.

class A {

    class B {
        final A this$0;
        B() {
            this$0 = A.this;
        }
    }

    class C extends B {
        final A this$0;
        C() {
            this$0 = A.this;
        }
    }
}