I don't know about the "sufficient" part but I personally liked his Java 1.1 book,
if you download the errata (corrections!).
On top of that you can study the new (with Java 2)
Collection interface and framework.
But I must add that
you should get, IMHO, two more books: Roberts and Heller's
The Complete Java 2 Certification Study Guide and William Brogden's
Java 2 Exam Cram, this last one for the couple of days before the exam.
My $0.02