Welcome!
First things first... It's only one exam for Programmer Certification.
Since you already know C++ you'll need, IMO, one book to teach you Java that's at the level of a C/C++ programmer AND one or maximum two books about Certification alone.
The official objectives are in
Sun Microsystems site.
I recommend as the book for programmers who want to learn Java,
Just Java 2 by Peter van der Linden, a known C author, or
A Programmer's Guide to Java Certification by Khalid A. Mughal and Rolf W. Rasmussen. Two strong contenders, IMO. I have both of them
For Certification exam study, THE COMPLETE JAVA 2 CERTIFICATION STUDY GUIDE by Roberts, Heller and Ernest and JAVA 2 EXAM CRAM by William Brogden.
When you feel comfortable with the language, you then should study the certification books above, definitely answering
every exercise in them.
Then there are mock exams on the Web. Here the situation is less clear because we already have seen
pretty bad questions, badly worded, ambiguous or plain wrong answers.
I will be putting together a few links to the ones I trust. I can recommend though without reservation, the site
Java Programmer Certification Exam And Training by Marcus Green.
This site (JavaRanch) has a shall we say,
cute little quiz in the form of a "Cattle Drive" game... look for it from the main page. Again it's a mock exam so
you should learn some Java first.
Hope this helped.
Ta ta for now!