Chapter 14. The Java Class Libraries

In the preceding chapters, reference was made to the contents of the Java API. One of the things that makes Java such a powerful programming language is the enormous collection of predefined classes and interfaces that you can access. Java API refers to these libraries that you can download from the Sun website, from the apache.org website, and from other sources. You'll find that with Java a lot of the low-level programming work has already been done for you. You can leverage off of the built-in classes when you are writing your own.

The libraries are divided into packages according to the general function of the classes and interfaces that they contain. When you download and install the Java SDK, you are also downloading and installing the J2SE libraries. Also available for downloading are the J2EE and J2ME libraries (also from the Sun website) and the Extensible Markup Language (XML) libraries that can be found at http://xml.apache.org. To refer to the contents of the Java libraries by their simple name , you must import part or all of the desired package into your program. Importing packages is covered in Chapter 11.

This chapter will provide a brief description of the classes, interfaces, and methods that are contained in the J2SE libraries. We won't cover all the packages in the J2SE libraries, nor will we provide details on all the classes and interfaces in the packages we do discuss. We'll focus on the library elements most commonly used in scientific or engineering programming.

The topics discussed in this chapter are ”

• Package naming conventions

• The core J2SE libraries

• The GUI libraries