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