Java: Cannot override abstract method passing subclass

Question

I have an abstract class

public abstract class SuperclassA{
   public abstract void method(SuperclassB b);
}

And an implementation

public class SubclassA extends SuperclassA{

   @override
   public void method(SubclassB b){
   }
}

where SubclassB extends SuperclassB.

My NetBeans editor complains that I am not overriding method. What can I do to actually pass a subclass to method?

Answer 1

In order to override a method of the base class, the sub-class's method must have the same signature.

If you want the overridden method to accept only instances of SubclassB, you can test for it :

public class SubclassA extends SuperclassA
{
   @Override
   public void method(SuperclassB b){
       if (!(b instanceof SubclassB)) {
           // throw some exception
       }
       SubclassB sb = (SubclassB) b;
       ...
   }
}

You can call that method as follows :

SuperclassA a = new SubclassA ();
a.method (new SubclassB ());