Rajesh,
An
SCJD exam taker has to know Swing, RMI/Object Serialization over TCP, Multithreading, File I/O, Jar and most of all standard design
patterns.
And I believe before downloading an SCJD assignment, you need to study or know nothing (as you must be
SCJP earlier you know the basic things). Download and then start studying topics accordign to your assignment --- you'll get at least one year to complete!