Clojure is a natural choice. One reason this book uses Java is that I wrote the first edition in 1998, this being the fourth edition. I still like Java simply because I use Clojure and JRuby a lot and Java interop is easy.

I love to write, and if I could get a world class Clojure coder (perhaps someone like Alex Ott, or someone with similar skills) to co-write, it would be fun to start over.