Java Platform API Packages

Introduction

The power of Java lies in the pre-existing functionality supplied by the Java platform Application Programming Interface (API). The Java platform API is a collection of packages that supply a set of classes ready for use in your programs. When you download and install the Java SDK or JRE you are also installing the Java platform API.

The Java platform is both a blessing and a curse to novice Java programmers. It’s a blessing because with the classes supplied by the Java platform you can write extremely powerful programs with minimal effort. It’s a curse because you must expend a lot of effort to learn your way around the Java platform API packages and the functionality they offer. If fact, of the total time you’ll spend learning Java, you will spend about 10 percent of your time learning the syntax of the Java programming language, another 10 percent learning object-oriented programming concepts, and the other 80 percent of your time learning how to use the Java platform classes in your programs. But don’t despair! You only need to know a small fraction of the Java platform API to write robust, well-behaved Java programs. Also, the Java platform classes you will use in this book will be introduced to you slowly as you progress through the text.

The purpose of this chapter then is to jump start your understanding of the Java platform API. I will show you how it is organized and what functionality it provides. I will also show you how to read a class inheritance hierarchy diagram so you can determine the full range of functionality a particular class provides. Knowing how to read a class inheritance diagram is a valuable skill that will pay huge dividends as you progress with your Java studies.

As I said above, in this book you will use just a small part of the Java Platform. However, once you know how to navigate the platform packages and how to read a class inheritance hierarchy you will have all the knowledge required to confidently approach the art of Java programming and add cool functionality to your programs.