Question

Possible Duplicate:
Overriding return type in extended interface – Bad idea?

Lets consider the following interface,

public interface Cat{
    public Object getCat();//returns any type of object
}

public interface DomesticCatInterface{
    public String somethinOnlyRelatedToDomesticCat();
}

public interface WildCatInterface{
    public String somethinOnlyRelatedToWildCat();
}

public class DomesticCat implements Cat, DomesticCatInterface{
    @Override
    public DomesticCat getCat(){
        return this;
    }

    @Override
    public String somethinOnlyRelatedToDomesticCat(){
        return "something";
    }

}

public class WildCat implements Cat, WildCatInterface{
    @Override
    public WildCat getCat(){
        return this;
    }

    @Override
    public String somethinOnlyRelatedToWildCat(){
        return "something";
    }
}

is this a good practice follow, when I need to get a reference from a class?

Answer 1

Instead of making getCat() return an Object, make it return a Cat. This you should be able to return any Class that implements Cat. In java 5 this is called Co-variant return types