I believe it is all about how things are explained. The textbook is a typical example of something written to look good and educated. I did not understand certain concepts so well as explained in Jia, so I had a look at some documentation a colleague gave me from a Java course he did and found amazingly simplistic explanations in the "Java cookbook" by Ian Darwin published by O'Reilly. It is unfortunately too large to email, but if you can get your hands on a copy tonight, it might make the difference between failing and passing....