About hiding and overriding

Question

Hi,can u tell what is the difference between hiding and overriding.
Is hiding only applied to class method(static) and overriding only applied to instance method?
It is a must to use "super" keyword to use a overridden method.Is that right?
And Look at the code below:
Can u tell why s.greeting is refer to static method of super while s.name() refer to method of sub?
What is type and what is class then? Any difference?
I have read the doc of Java Spec and still do not feel clear about it.Thank you for attention.
class Super {
static String greeting() { return "Goodnight"; }
String name() { return "Richard"; }
class Sub extends Super {
static String greeting() { return "Hello"; }
String name() { return "Dick"; }
class Test {
public static void main(String[] args) {
Super s = new Sub();
System.out.println(s.greeting() + ", " + s.name());

Answer 1

It's not necessarily a must to use the "super" keyword in an overridden method. If your class extends some class called "TopClass", and "TopClass" has a constructor, then you must use the super keyword as the first statement in the constructor of your class.
When you extend a class, your class becomes a type of that class. If you want to override methods, the only requirement (that I know of) is that only the method's body can differ from that of it's super class.
i.e.
Here's a method from some super class:
public boolean mySuperMethod(String s) {
System.out.println("Hi");
return true;
Here's the overridden method from an extended class:
public boolean mySuperMethod(String s) {
boolean b = false;
return b;
As you can see, you can do whatever you want inside the method, but everything else has to stay the same (as far as I know).
Here's another example that I did a while back. It's a checkbox that can't be tabbed to and can't accept user actions. I used it simply as an indicator for something.
import java.awt.*;
public class NonTraversableCB extends Checkbox
     public NonTraversableCB()
          super();
     public NonTraversableCB(String label)
          super(label);
     public boolean isFocusTraversable() {
          return false;
     public void processEvent() {
          return;