Somnath Mallick,
Please find my answers:
Associate Level
There are two versions of Java associate exam.
1. Oracle Certified Associate, Java SE 7 Programmer
Oracle Certified Associate, Java SE 7 Programmer certification provides basic knowledge required to program Java code.
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=413
2. Oracle Certified Associate, Java SE 5/SE 6
Oracle Certified Associate, Java SE 5/SE 6 (Formerly Sun Certified Java Associate (
SCJA) ) certification provides basic knowledge required to manage a Java project. You can expect Java EE and Java ME questions as well in this exam along with basic Java SE skills.
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=51
Programmer
OCP, Java SE 7 (currently under development)
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=407
OCP, Java SE 7 Upgrade Exam (currently in BETA stage)
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=397
OCP, Java SE 6
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=166
OCP, Java SE 5
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=161
Developer (assignment type exam)
Oracle Certified Master, Java SE 6 Developer (Formerly Sun Certified Java SE 6 Developer (
SCJD 6)) certification tests Java programming experience.
You need to complete 1Z0-855 Java Standard Edition 6 Developer Certified Master Downloadable Project (Step 1 of 2) and 1Z0-856 – Java Standard Edition 6 Developer Certified Master Essay Exam (Step 2 of 2) to achieve this certification.
Read this article about this exam =>
http://www.epractizelabs.com/blog2/?p=128
Look on JavaRanch links about study guides and mock exams.
Good luck for your preparation !