Bill, if you read the "Acknowledgments" in the book, you would understand the real motivation behind writing this book. I have trained and accessed several trainers of the Sun Authorized Training Centers since 1996 and thus have been in constant touch with Core Java. During the delivery of SL275 and several other courses from Sun's curriculum, I realized that there were many errors in the material available to these aspiring candidates. The early versions of the official curriculum too had a few technical errors. So I always wanted to bring out the material which would be technical accurate. I feel that I achieved it with the support from Oracle team - just to mention two important names, John Pampuch, Director Java VM technology and Danny Coward, Chief Architect Java SE 7 who provided a technical review of the manuscript "twice". As I said, I am satisfied with the contents accuracy. However, there may be a few errors, specifically typos which may have gone unnoticed. I request the readers to bring such errors, if any, to my notice and we will publish the errata on the book's site.
The book is for professional programmers who want an authentic and accurate information on Language syntax and core libraries. As I mentioned in my another post, it can also be used as a classroom text. It is definitely not a begineer's tutorial on Java.