vijaya,
A score of 50% on my mock exams isn't bad. If you go to jdiscuss.com and click on the link called "Compare
SCJP Scores" you will see that people that score 50% on my mock exams typically score much higher on the real exam.
My exam is best used as a workbook. Just work through the exams, read the detailed answer explanations, and learn all that you can.
The key to learning and retaining information is to get your brain actively involved in the process of solving a problem or analyzing a detailed explanation of a problem that interests you. In contrast, the key to rapidly inducing sleep is to passively read a textbook that attempts to lecture you on a topic that doesn't really spark your interest. That's why learning from my mock exams and from my book does a great job of engaging your brain and helping you to develop a better understanding of the material.
School is getting started soon. If you know of anyone that will be studying
Java programming in school this semester, then please let them know that my book is a great study tool for mid-term and final exams. It's not just for the SCJP exam.