Override member data in subclass, use in superclass implementation?

Question

In Java, is it possible to override member data in a subclass and have that overridden version be the data used in a super class's implementation?

In other words, here's what I am trying to get to happen, and it's not happening:

abstract public class BasicStuff {
        protected String[] stuff = { "Pizza", "Shoes" };

        public void readStuff() {
                for(String p : stuff) { 
                        system.out.println(p); 
                }
        }
}

..

public class HardStuff extends BasicStuff {
        protected String[] stuff = { "Harmonica", "Saxophone", "Particle Accelerator" };
}

This invocation:

HardStuff sf = new HardStuff();
sf.readStuff();

... prints Pizza and Shoes. I want it to print the latter instead.

I recognise that this is rather poor hierarchical OO practice; I needed it for a very specific case as I am doing something with XML configuration and reflection.

Is there a modifier that can make this happen?

And yes, I do recognise that there are wrappers one can use to get around this problem in my subclass, i.e. by indicating that the contents of stuff[] are now stored in an array with a different name, for instance. I'm just trying to keep this simple, and am curious in principle.

Thanks a lot in advance!

Answer 1

This way you are hiding the parent variable stuff with the defined stuff.

Try giving value to stuff in the initialization block (or in the constructor):

abstract public class BasicStuff {
  protected String[] stuff;

  {
    stuff = new String[] { "Pizza", "Shoes" };
  }

  public void readStuff() {
    for(String p : stuff) { 
      System.out.println(p); 
    }
  }
}

..

public class HardStuff extends BasicStuff {
  {
    stuff = new String[] { "Harmonica", "Saxophone", "Particle Accelerator" };
  }
}

Answer 2

I believe you must interpose an accessor method, i.e., use:

    for(String p : getStuff()) {

in the superclass, and add:

    protected String[] getStuff() { return stuff; }

wherever you have a protected String[] stuff redefinition.

Overriding really applies to methods, not data (at least, that is so in the Java model; some other languages do things differently), and so to get the override effect you must interpose a method (typically a dirt-simple accessor, like here). It doesn't really complicate things at all, it's just a very simple way to instruct the Java compiler to use, intrinsically, the "extra level of indirection" that your desired behavior requires.