You can get the course description and content here:
SL-285
Honestly I agree with Andrew, self study with no guidance is tough. Yet given the course content and the actual assignment do have some discrepancies. Eg the assignment doesn't allow to use
JDBC and the course cover JDBC. It's good to know as if for building real world apps.
I personally think understanding design
patterns and how they apply to sample apps/case study is crucial to help building SCJD assignment. The other things like RMI/Sockets and Swing is practice through experiement.
By the way, I didn't take SL-285.