If you're programming Java at all, you're going to need a hand knowing which classes Java has. It would also be nice to know which methods and fields those classes have. It would ALSO be nice to have a description of those classes, methods, and fields, as well as related classes, deprecation information, and much more. Hard to find all that much information in one place, right? Wrong. In fact, Sun's Javadoc gives you all that and more.