Right now, all of our classes are finishing up with teaching the AP computer science course and all of the requirements given in the AP JAVA subset.
If you are looking for review material, here is a list that I've found to be valuable to my students.
The one that I have used for 11 years now has been the book by Skylight Publishing called Be Prepared for the AP Computer Science Exam in JAVA. The book is written by Maria Litving along with Roger Frank, Judith Hromcik, Dave Wittry and Gary Litvin. All contributors except for Gary are AP Teachers and have been involved with the CollegeBoard either as Readers, Chief Readers, or Exam contributors. The book reviews all concepts required for the exam and has 2 practice exams in both the A and AB part. My students in the past have told me that if you can pass the Litvin review book tests then you'll get a good score on the AP exam.
Eimacs.com has the exam online if you want your students to review that way.
The 2nd book that I required my students to get was the McGraw-Hill book called 5 Steps to a 5 AP Computer Science written by David Levine and Kathleen Larson. David is a college professor and Kathleen a high school AP Computer Science teacher.
The layout of the book is similiar to the Litvin book and it too comes with 2 practice exams for the A & AB exam. The students liked the practice exam especially the free response questions because they were easy. This book gives students success on the taking the practice exams but they do find the Litvin book harder.
Roselyn Teukolsky has a reveiw book that Barron's puts out called the AP Computer Science 2007 Levels A and AB. I don't use this resource book because of time.
Barbara Cloud who teaches at Colgate University and Chris Nevison also a Professor at Colgate and was the Chief Reader a couple of years ago has some AP CS resources that you need to purchase but it has good reviews and 2 AP exams for students to review.
Georgia Tech has a nice site where you can take A or AB multiple choice questions online and you get feedback from your answers.
Finally, the CollegeBoard site has several Free Response Questions from past years to give your students and you can purchase the 2004 AP CS exam from the CollegeBoard with gives you an idea of what they test in JAVA.
Better hurry up and start reviewing because you only have about a month left for the exam. Good luck!!