Question

I have a subclass named child which inherits a class named parent. I am trying to override the method in the super class. I have experimented a little. I have created the overriden method with its return type short which is the subtype of int. As far I know I can do so. And the method is legally overriden. whenever I call the method with the reference of the super class, the compiler generates an incompatible return type error. What’s the problem here ? My code is given below:

class parent
{

    int test()
    {
        System.out.println("called inside parent\n");
        return 1;
    }
}

class child extends parent
{

    short test()
    {
        System.out.println("called inside child\n");
        return 1;
    }
}

class Myclass
{

    public static void main(String[] args)
    {
        parent a=new child();
        a.test();
    }
}

Answer 1

short which is the subtype of int

Wrong, it is not. The value range of short is a subset of that of int, but this is a totally different issue. A short value can indeed be converted to an int (even implicitly), still a short is not an int.

Primitive types are not regular classes, so these can’t have supertype/subtype relationships. Therefore you can’t use contravariance of return type in this case: once you declared a return type of int in the base method, all of its overrides must return int.