Java Utilities cover java.util and java.util.jar API, as standard on the JDK or Java 2SE.
The Java Platform
In this excerpt from O'Reilly & Associates' Java in a Nutshell, 4th Edition, David Flanagan shows you a number of the Java 2SE platform packages, using examples of the most useful classes in these packages.
The Preferences API in Java 2SE 1.4 (Merlin)
Explore the Preferences API as it is implemented in Beta 2 of J2SE 1.4 (also known as Merlin).