Java 6 Illuminated: An Active Learning Approach, 2nd Edition

Figure 10.2

The RollABall Class

Hierarchy

Object

Component

Container

Panel

Applet

JApplet

RollABall

656 CHAPTER 10 Object-Oriented Programming,Part 3: Inheritance,Polymorphism,and Interfaces

Let’s look at an example of inheritance that we’ve already used. We’ve used

the extends keyword whenever we wrote an applet. For example, we defined

our rolling ball applet in Chapter 6 as:

public class RollABall extends JApplet

This means that the RollABall class inherits from the JApplet class.

Because our RollABall class extends JApplet, it inherits more than 275 meth-

ods and more than 15 fields. That’s because the JApplet class is a subclass of

Applet, which is a subclass ...