Java generics - overriding an abstract method and having return type of the subclass

Question

I am trying to create a set up where a set of subclasses override a superclass. This superclass contains an abstract method - the return type of which would ideally be that of t

Answer 1

Here is how to do it (Since JDK 1.5 there is this thing called covariant return types, where something like this is possible).

abstract class SuperClass>{
  public abstract T getSelf();
}

class SubClass extends SuperClass {
  public SubClass getSelf() { return this; }
}

public class Generics {
  public static void main(String[] args) {
    System.out.println(new SubClass().getSelf());
  }
}

Notice a similar class generic definition with Enum (http://download.oracle.com/javase/1,5.0/docs/api/java/lang/Enum.html)

See what happens behind the scenes (by using javap SuperClass SubClass):

class SubClass extends SuperClass{
    SubClass();
    public SubClass getSelf();
    public SuperClass getSelf();
}

abstract class SuperClass extends java.lang.Object{
    SuperClass();
    public abstract SuperClass getSelf();
}

Notice how the subclass method has a different return type, which is a subtype of the super method return type.

Btw, notice that public SuperClass getSelf(); in class SubClass is actually a synthetic method.