How can I access variables outside class scope but inside parent class scope?

Question

I have an exam example which ask whether or not can I access the x variable containing the value 1? The solution is that I can, but I'm interested how exactly?

class A {
    int x = 1; //this is what I need access to.
    class B {
        int x = 2;
        void func(int x) {...}
    }
}

Why do exams these days always concentrate on edge cases that are often indicative of poor practice? — Bathsheba, Jul 02 '17 at 16:48

score 3 · Accepted Answer · answered Jul 02 '17 at 16:44

class A {
    int x = 1;

    class B {
        int x = 2;

        void func(int x) {
            System.out.println(A.this.x);
        }
    }
}

Using example:

public class Main {
    public static void main(String[] args) {        
        A a = new A();
        A.B b = a.new B();

        b.func(0); // Out is 1
    }
}

score 1 · Answer 2 · answered Jul 02 '17 at 16:49

1

To access the parent instance, you use the this keyword as in ParentClassName.this

The child class must not be static

answered Jul 02 '17 at 16:49

kosgeinsky

508
3
21

score 1 · Answer 3 · answered Jul 02 '17 at 16:53

Yes you can access variable x with value 1.

Here A is your outer class and B is Non-Static inner class.

To access variable x of outer class A you could do something like this

class B {
    int x = 2;
    void func(int x) {
      System.out.print(A.this.x +"  and  "+x);
    }
}

How can I access variables outside class scope but inside parent class scope?

3 Answers3