I have started to read book
SCJP: Sun Certified Programmer for Java Platform Study Guide: SE6 (Exam CX-310-065). This reading is great for huge spectrum of programmers, even senior java one has to find places where he can gain new knowledge. I had to continue reading SCJP book despite I'm currently working on project having .NET behind. It helped me to understand stuff "behind the wall", what compiler allows, how works inheritance. The book covers all materials likely using within technical interviews :-) You couldn't be caught so easy :-)
