My score in exam lab was over 80%. Please note there are a few errors in the exam lab exam. However the value of this tool is it gives you a reasonable facsimile of the actual exam and the threading class questions will be of great value not only on the exam but for
thread programming in general. The sun exam also emulates the actual exam and content well. Even though this exam costs a few dollars to purchase it has a lot of questions very similar to the exact exam style. If you see a question in their exam a similar question will likely be on the real exam. Look at the question from a logical point of view and then concentrate on the whole area. For example: If there is a question about StringBuffer then
you should be familiar with the StringBuffer class's constructors and methods. If you do not wish to purchase Sun's practice exam the exam guidelines are a good enough guide on what to study
Sun SCJP certification page I purchased the exam because I figured it would give me an idea on what the real exam would be like. The exam was difficult in spots and easy in others.
As far as the API contents you need to know, it is the IO classes and the collection classes. Also you need to know the Thread and Runnable classes. You also need to fully understand how to set the classpath for JAR files, set the System properties, and compile files(Remember the exam covers Unix paths). All the mock exams cover fundamentals, OO concepts, flow control, Declarations intialization and scoping. This should not be a problem for most of you. So it really boils down to which API's to memorize and setting system properties, compiling and running programs from the command line and of course threading. The exam does have questions on Garbage collection too which is in most mock exams as well.
The best overall material was "A Programmer's Guide to Java SCJP Certification". The sun exam guidelines
Sun SCJP certification page are the next best thing to concentrate on for API and exam content.