Hi Jyotsna,
The best place to start is with the exam objectives posted by Sun at
http://suned.sun.com/US/certification/java/exam_objectives.html#programmer For useful books, check the links at the top of the forum page. Most people prefer RH&E and the Khalid Mughal book along with Bill Brogden's Exam Cram. There are reveiws of each in the Bunkhouse section as well as on Amazon.
Also, check
Maha Anna's pages here at JavaRanch and
Marcus Green's site.
Hope that helps.
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Jane Griscti
Sun Certified Programmer for the Java� 2 Platform