Google around searching on "java for c++ programmers" (with the quotes), you
can get some good tutorials that way.

Go to www.javabook.org for an actual college text that the author
makes available in electronic form.  It isn't a C++ to Java book, but
what you need to learn is Java, not the differences (and similarities)
between C++ and Java.  If you decided to take up Japanese after
learning Spanish, would you want a Spanish to Japanese book, or just a
book to learn Japanese?

Another electronic book that you may want to look into is "Thinking In
Java" by Bruce Eckel.  You can find it in a couple of different ebook
formats.

Find the college board website.  You can find information there about
what you need to learn for the AP exam.

Of course, your background with C++ will help to work through the
first half-dozen chapters pretty quickly.  Much of the syntax is the
same, since Java started out as an attempt to modify C++.  You
indicate that you are familiar with OOP, which is often the biggest
hurdle for people coming from C++ (since OOP is semi-optional in C++,
but not in Java).  That will serve you well.

Download the Java SDK from Sun (nice and free).  Be sure to also
download the documentation (also free).  Also, you can find several
free editors to use.  Here are two that I like:

DrJava (drjava.sourceforge.net)
   Written in Java and created by Rice University
   Has a very handy interaction window where you can experiment with
   code snippets.

JCreator (www.jcreator.com)
   Freeware and Shareware versions.
   Native Windows program (written in C++) - if you have an older
   machine the extra speed will be appreciated.
   
Here are a couple of differences that you might as well learn now.  
1.  Java has only single inheritance.  That is a good thing.
2.  No pointers in Java.
3.  Java tends to be much "wordier" than C++
4.  Most things are easier to do in Java, but there are some things
   that are harder to do than in C++ because they have to be done
   in a cross-platform manner.  Get used to it, it won't go away.
5.  Console i/o is a pain in the ... in Java.  It is one of the
   things referred to in #4.

JAVA for C/C++ Programmers by Michael C. Daconta   This is a special book to
me and I will never get rid of it.  This book and Java has led me to study &
understand more things than I ever imagined.  The code snippets are
available online if you can't find one with a CD.  Check out his website; I
think it can be found searching his name on google.

Daconta even lists and discusses a little database of his called EZDB in the
book.

Try www.amazon.com or www.half.com to find it used or new.

http://www.amazon.com/exec/obidos/tg/detail/-/0471153249/qid=1078203300/sr=1
-1/ref=sr_1_1/102-2491278-1772919?v=glance&s=books

I somewhat agree with the argument aginst Daconta's book but It reads very
well and shows direct corelations between C++ andd JAVA.  I was never able
to learn anything from ONE book though.  You will need several as well as a
Class Library Reference.

Sean

One thing to keep in mind is that you don't just have to learn Java,
you have to learn what is on the AP test.  I understand Jon's
criticisms of the book that I mentioned, but it DOES cover the AP
subset, and is in use in AP courses.  (Plus, it has been revised since
Jon first read it, and it is FREE!!!)

You will also need to get a copy of the case study that the AP is
using.  If you can't get it from the AP site yourself, I can help you
with get it.