Normally its good to stick with one book, complete it, then go for solving the mock exams - lot of them -and what ever concepts you feel you are weak in, go through those concepts from more than one book. Book of khalid moghul is also nice one, taking you much deep. And ranchers here are also quick enough to answer your doubts. But most importantly try to code your doubts, not only the doubts gets clear, but you also learn many other relative things - its priceless.
Preparing for OCPJWCD 6.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com