The Well-grounded Java Developer – Vital Techniques of Java 7 and Polyglot Programming, Benjamin Evans, – 2013
Java programmers will want to read this book. Java 7 has NIO2, allowing input/output on multiple connections concurrently within a single process. The book also introduces several new languages that run on the JVM. Groovy gives you the convenience of dynamic typing as seen in scripting langages. Scala makes concurrent programming easier using immutable classes. Clojure gives you safer programming. 450 pages.