Question

I have a interface called ABC. I also have an abstract class PQR and there are 3 classes which extend this abstract class.

For example:

abstract class PQR {
    //...
}

interface ABC {
    //other methods....
    PQR returnRightClass();
}

class X extends PQR {
}

class Y extends PQR {
}

class Z extends PQR {
}

Now there are classes which implement the ABC interface. So what should I do to get the right class from X, Y, and Z?

Answer 1

There is nothing wrong with returning an abstract class, though it is recommended to use interfaces as much as possible. If you can make PQR an interface, then do so. But if not, no worry.

Now there are classes which implements ABC interface. So what
should I do to get the right class from x ,y ,z?

Just make sure each implementation of returnRightClass() in each class implementing ABC returns a proper instance of PQR (x,y or z).

EDIT

To answer your question:

public MyClassX implements ABC {

    public PQR returnRightClass() {
        return new x();
    }

}

Or

public MyClassY implements ABC {

    public PQR returnRightClass() {
        return new y();
    }

}

Or

public MyClassZ implements ABC {

    public PQR returnRightClass() {
        return new z();
    }

}