I was a
JAVA beginner last year. I started off with the Head First Java book. Then moved on to the K&B book. In the last 1 month, I did about 4-5 passes of K&B and took lots of mock exams (mostly from links posted around here or using Google). I also took a mock exam from the the CD of the K&B book (MasterExam). Finally, I did the exercises from the K&B book over and over again. On the last day, I just brushed over the 2 minute drill from K&B.
If you face difficulty with Collections and Generics, I'd highly recommend Chapter 16 from Head First Java. That simplified things in that area for me.