Class Reference Tool

I wanted to ask you if anyone may know of a good Class Cross reference tool, or book, that will help in figuring out which classes to use in creating Java programs?

I've tried for years to make sense of all the classes and the only way i've been able to do it is by looking at code examples!

Is it possible to take the Sun documentation a step further and add some kind of additional intelligence to the linkages between classes and present that in such a way that it will become more obvious which classes to use when and where?

It's been awhile since i've gotten back into the Java mode and everytime i come back, it's like starting over all over again!

I assumed that someone would have developed such a tool by now, but after surfing the web for over a week, i've only seen code analyzers and code documenters, but nothing to really make sense of the massive number of classes and relationships!
Thanks from BobC

Well, Here is a set of UML-like diagrams of the Java API classes. You'd probably also really enjoy the book The Java Developer's Almanac which explains how to use the API classes one by one, each with code examples. It's a gold mine, really. There's a web site for the book as well, with lots of the code samples in electronic form.
[ January 22, 2004: Message edited by: Ernest Friedman-Hill ]

I second Ernest's opinion, the Almanac rocks! I also like the Java Cookbook, but I'm not a big fan of Java in a Nutshell.