As a general tip I have to recommend testing this sort of thing yourself!
We've listened to thousands of ranchers who studied for these Sun Java exams, and everyone who does really well writes LOTS and LOTS of code while they are studying. So this would be a case where you should type the code in, FROM THE COMMAND LINE and NOT an IDE, and test it. Then, once you've typed in what's in the book, play around with it - change stuff, try stuff out, and experiment. That's how you're really going to learn this stuff.
Finally, I can say that the teams that create these tests write and test LOTS of code (from the command line), while the questions are being created. And, Kathy and I write and test LOTS of code while we're writing our books.
Being a good programmer is like being a good tennis player. You can't just read about hitting tennis balls, you have to go out on the court and hit a lot of tennis balls.
Spot false dilemmas now, ask me how!
(If you're not on the edge, you're taking up too much room.)