This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Regular expression in Java aren't different from regexps in other languages. They use the Perl syntax for the most part. Or are you looking an introduction to regexps in general? Then http://www.regular-expressions.info/ is for you.
Examples of using the java.util.regex package can be found here.