The Power of Inheritance
You have used inheritance every time you worked with one of the standard Java classes such as String or Integer. Java classes are organized into a pyramid-shaped hierarchy of classes in which all classes descend from the Object class.
A class of objects inherits from all superclasses that are above it. To get a working idea of how this operates, consider the JApplet class. This class is a superclass of all applets, browser-based Java programs that use a graphical user interface framework called Swing. The JApplet class is a subclass of Applet.
A partial family tree of JApplet is shown in Figure 12.1. Each of the boxes is a class, and the lines connect a superclass to any subclasses below it.
Figure 12.1. The family tree ...
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