The ebook - Lots of multiple choice questions, what is on the exam, common mistakes, videos, and practice exams.

Java Visualizer - Let's you step through Java code and see the values of all of the variables

Java Bat - of short practice problems in Java. Some of the problems have hints and answers.

Practice It - http://practiceit.cs.washington.eduLots of practice problems in Java.

AP CS A Massive Open Online Course (MOOC) -

Alice 3 -
Let's you do drag and drop programming of 3D characters in a 3D world.
How to guide at

Greenfoot -
Makes it easy to create 2D animations and games in Java.