I'm wondering who the target audience for your book is? Are you assuming some programming experience, or is it for absolute beginners who have never programmed a thing in their life?
At the company I work for we tend to take on some junior and graduate software engineers each year. They come in with some limited programming experience but not always Java. Would your book be suitable for those guys who are familiar with the basics of how to code but need to learn the Java specific syntax, constructs, and paradigm?
Tim, My "Java For Dummies" book is mostly for beginners.
I have another book "Java Programming for Android Developers For Dummies" that's more appropriate for someone with some programming background in a language other than Java. (I think the book is worthwhile even if you're not aiming to write Android apps.)
In the other direction, I have yet another book "Beginning Programming with Java For Dummies" that's for absolute beginners. This book emphasizes the basic ideas of computer programming (mostly imperative-style programming) using Java as a vehicle for learning.
I might add that none of these books are "fluff." Some people avoid books in the For Dummies series because they think the books are mostly jokes and very little content. But I've been teaching computer programming to college students and computer professionals for several years. So when I wrote the books, I tried to anticipate and answer the kinds of questions that people typically have about each topic (... along with some good jokes).