I'll jump in here and say that the study guide book was the only book that I used for the exam, however, I had already learned some Java. I guess what I am saying is that you need to start with HFJ if you need to learn Java but if you know some Java and just want to study for the exam then I think you can get by with just the study guide book.
We try to have a focus or intention for each book. HF Java is focused on teaching you basic, fundamental Java. The study guide is designed to prepare you for the SCJP exam... it assumes you already have basic Java skills
Spot false dilemmas now, ask me how!
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