Access outer class function from Object of Inner Class

Question

I know there are similar question put up related to this issue, but however, I wasn't able to resolve my issue. I've tried to simplify my problem to the following code -

class Outer
{
    Outer()
    {}

    class Inner
    {
        Inner()
        {}
    }

    void func()
    {
        System.out.println("Outer");
    }
}

public class Nested
{
    public static void main(String args[])
    {
        Outer oo = new Outer();
        Outer.Inner ii = oo.new Inner();

//          ii.func(); I know this won't work


    }
}

Can I call outer class function "func()" from object of inner class "ii"..?? If yes, how?

Answer 1

Short answer: the reference to Outer.this is private in Inner so you cannot access the reference to the Outer instance from an instance of the Inner.

You can export this reference thus:

class Outer {
    Outer() {
    }

    class Inner {
        Inner() {
        }

        public Outer getOuter() {
            return Outer.this;
        }
    }

    void func() {
        System.out.println("Outer");
    }
}

Then you can simply do:

ii.getOuter().func();

Answer 2

Use Outer.this.func() from the inner class. Do note that you can only do this from the inner class, not from outside.