You can download the sourcecode for the examples in the book from any of:
The sourcecode download also includes ancillary files, such as .gif files containing icons for instance, where they are used in the examples.
If you have any questions on the fine formal detail of Java, the reference works we've used are:
The Java Language Specification, Second Edition (The Java Series) James Gosling et al., Addison-Wesley, ISBN 0-201-31008-2
Other sites of interest are:
http://www.wrox.com for support for this book and information on forthcoming Java books.
http://p2p.wrox.com for lists where you can get answers to your Java problems.
http://java.sun.com/docs/books/tutorial/index.html for the JavaSoft tutorials. Follow that Java trail.
and for online magazine reading and opinion, check out:
We also like the Java Developer Connection, subscribe to it at http://java.sun.com/jdc