Chapter 9: Packages and Access

Overview

Congratulations! At this point, you know almost all there is to know about Java's classes. The remainder of this book will look at how classes interact, and it will present many of the core Java classes that the system provides to make your life easier. To make an analogy with the life sciences, we are pretty much done with class anatomy (the analysis of the internal structure of a class) and are ready to tackle class sociology (the study of how classes interact).

This chapter will first look at packages, which are organizations of interrelated classes. Once you understand packages, you will have a good foundation for understanding access. Java has several keywords that control access, including public. This means that by the time you finish this chapter, you will know why your application classes and your main methods have been marked as public.

By the way, in this edition of this book, this chapter has no animated illustrations. The information presented here doesn't benefit from the animated illustration model. However, if you can think of a concept from this chapter that would look good as an animation, please send us your idea in detail at [e-mail]. If we use your idea in the next edition, we will give you a credit.