Even if you have never had the opportunity to work with regular expressions in any language, even if "regular expressions" means nothing to you, this book will make you an expert very quickly. The entire book is less than 250 pages and yet the book gives almost perfect coverage of the java.util.regex package.
The best part of this book is that it serves both as a tutorial for anyone who the topic is new to, and as a reference for anyone who is already familiar with regular expressions in Java. It is that rare tutorial that you can keep by your desk even after you mastered the material.
I should add a couple of statements. First, Max and I are both moderators at JavaRanch. Second, Max is an expert at martial arts and I am fairly certain that he could beat the hell out of me without having to break a sweat. But neither of those things affected my review. ;-) I have been kidding Max because it took so long to finish this book but it was well worth the wait. Great job, Max!
You can see the full official Amazon review here.