Java, A Beginner's Guide, 5th Edition, 5th Edition

Introducing Nested and Inner Classes

In Java you can define a nested class. This is a class that is declared within another class. Frankly, the nested class is a somewhat advanced topic. In fact, nested classes were not even allowed in the first version of Java. It was not until Java 1.1 that they were added. However, it is important that you know what they are and the mechanics of how they are used because they play an important role in many real-world programs.

A nested class does not exist independently of its enclosing class. Thus, the scope of a nested class is bounded by its outer class. A nested class that is declared directly within its enclosing class scope is a member of its enclosing class. It is also possible to declare a nested class ...