Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Useful Unavoidable (?) Boredom

If you are aiming at Java Programmer certification (and only in this case) do buy this book. It is an excellent resource to test and amplify your skills. It offers clarity, depth , good code examples and more than enough material to challenge your current understanding and knowledge of Java. Don't expect it to be an easy or pleasant read however. It is a lean and mean certification guide, just the meat, no bells and whistles. It does give new meaning to the word "arid" but in doing so it offers very effective help to get your beloved certificate. The review questions and mock test are also excellent. As a side note, I don't think people should need to be "certified", cheese does.