[CaptainMorgan]

Your code didn't compile for me either, but the following did:

Code:

public class Jupiter {
  public static void extractUsers() {
    System.out.println("Superclass output");
  }
} 

public class Moon extends Jupiter {
  public static void extractUsers() {
    System.out.println("Subclass output");
  }
}

You can't override a static method as you did above, but the above code I posted does work. I'm not sure about your abstract method because I don't see one.

EDIT: see here for great info on the matter.