Just to echo Jess, the book does indeed cover 1.5. Oh, and one caution: looking things up in the index can give away solutions. Some puzzles are indexed by the underlying mechanism that makes them work, and you have to figure this out for yourself when your solving the puzzle. Don't say we didn't warn you
Josh and Neal
P.S. Along similar lines, don't even thing about reading Appendix A (Catalog of Traps and Pitfalls) before doing the puzzles. It will ruin them for you. Appendix B, on the other hand, makes a fine read independent of the rest of the book. It explains all of the optical illusions. Try reading it to your kids and showing them the pictures. My kids love optical illusions, and so do Neal's.
Joshua Bloch <br />Author of <a href="http://www.amazon.com/exec/obidos/ASIN/0201310058/ref=ase_electricporkchop" target="_blank" rel="nofollow">Effective Java</a> and coauthor of <a href="http://www.amazon.com/exec/obidos/ASIN/032133678X/ref=ase_electricporkchop" target="_blank" rel="nofollow">Java Puzzlers</a>
subject: Question for Authors: does the book cover J2SE 5.0?