This is a very, very important section! The Java Application Programmer Interface (API) is a vast collection of libraries. Luckily, it is well documented, and the documentation is easily accessed using a browser starting at http://java.sun.com/docs/index.html
You can also download the html and install it locally. I prefer to download it because local access is faster than web access, and we're mostly Type A individuals in programming. However you do it, start up your favorite browser and browse the URL for the Java API for the release you installed on your computer. When the page comes up, set a bookmark for it. Your browser should be displaying something like Figure 4-1.
Figure 4-1. The API documentation
This is ...