Question

I have the following abstract classes:

public abstract class AbSuperClass1<K,S> {
    //class definition
}

and:

public abstract class AbSuperClass2<K,S> {
    public abstract <Q extends AbSuperClass1<K,S>> void method(Q arg);
    ...
}

I then have two concrete implementations

public class Concrete1 extends AbSuperClass<String, String>{
    //class definition
}

and:

public class Concrete2 extends AbSuperClass2<String, String>{
    public void method(Concrete1 arg){
        //method definition
    }
}

This will not, however, compile, as Concrete1 is not recognised as a valid type for the argument of method in Concrete2, but as far as I can see Concrete1 is of the correct type, since it extends AbSuperClass1.

Where am I going wrong?

Answer 1

Eclipse suggested adding this method:

@Override
public <Q extends AbSuperClass1<String, String>> void method(Q arg) {
    // TODO Auto-generated method stub

}

Another thing you can do, is add this type parameter to the class:

abstract class AbSuperClass2<K,S, Q extends AbSuperClass1<K,S>> {
    public abstract void method(Q arg);
}

and

class Concrete2 extends AbSuperClass2<String, String, Concrete1> {
    public void method(Concrete1 arg) {
        //method definition
    }
}