Java Class Library organization

All the classes of the library are put in packages. The most important package names start with either:

• java
• javax

The distinction between the two is mostly for historical reasons. Modern, reputable Java SE implementations implement classes from both the packages. There are more public classes, though. A few assorted classes are put in packages that start with org, such as org.w3c and org.xml, but we'll ignore these classes in this book.

Vendors have the freedom to add their own classes to their library. In the case of Oracle's implementation, these classes reside in packages that start with the com.sun, sun, or com.oracle prefix. However, it is recommended that you use add-on libraries instead of the classes in these packages.