Java Puzzlers

Just finished "Java Puzzlers : Traps, Pitfalls, and Corner Cases" By Joshua Bloch and Neal Gafter.
Very interesting book - learned a lot of interesting things , and clarified a bunch of others :-)
Takes a bit longer than a 'normal book' - just too tempting to solve all puzzle's : leading to me breaking my head on a few of them and having to give up finally after a long haul.
Highly recommended.