Actually I don't think it's a very good book. Its main redeeming feature is that it rather brutally covers what you need for the exam and very little else - where it does diverge one is tempted to wonder why what they're diverging into isn't on the exam, since it's usually something fairly critical. It also has a CD with a mock exam (which is harder than the real exam due to not telling you how many options you need to choose for each question), which is undoubtedly useful.
Unfortunately it also seems unsure of its target audience, and there are places where it talks at length of the sort of thing any programmer should know (like deadlocks), but other places where it assumes you already know a fair bit and just want to get the details on how
Java does things. There are also a few rather dubious descriptions (no, StringBuffer.delete does NOT take a zero-indexed and then a one-indexed parameter - the second one is zero-indexed and means 'up to but not including this character'. A hairsplitting distinction perhaps, but one that's much less confusing).
Also unfortunately I can't recommend a better one, but I would recommend reading quite widely on various Java topics, especially anything you find difficult. Somewhere out there is probably an explanation which makes more sense to you. It's certainly been helping me in my preparations.
