Question

I have two classes and an interface shown below.
Quick summary: Interface Winterface, Class Big, Class Little that extends Big and implements Winterface.

public interface Winterface {}


public class Big {

    public int hello = 88;

    public Big() {}

    public void theMethod() {
        System.out.println ("Big was here: " + (this instanceof Winterface) + ", " + this.hello);
    }
}

public class Little extends Big implements Winterface{

    private boolean hello = true;
    public Little(){}

    public void theMethod() {
        super.theMethod();
        System.out.println("Little was here: " + hello);
    }

    public static void main(String [] args) {
        Little l = new Little();
        l.theMethod();
    }
}

When I execute the main in Little, I get the following output

Big was here: true, 88
Little was here: true

my question is, how can

1) (this instanceof Winterface) return true but

2) this.hello be 88?
If this.hello = 88, then this = Big, which isn’t an instance of Winterface.

I do not understand how this is possible, thanks in advance

EDIT: THANKS everyone I understand now that ‘this’ refers to little, which is a Big and implements Winterface. Since the method is being called as super.theMethod(), the variable ‘hello’ available is the one in Big even though ‘this’ refers to little.

Answer 1

this can only be one class. However this.hello is the field accessible to that class.

As this can only be one class it is a Little which has a parent Big and implements Winterface When you call a method in its parent which can only see hello that is what it sees.

i.e. Java supports polymorphism for methods but not fields.