Although Java 9 is now out and this book was written way back when Java 7 was new I still found this to be a very useful and educational read. The book explains the fundamentals of the Java platform (e.g. bytecode, garbage collection) and programming principles in general (e.g. concurrency, dependency injection, functional programming) in a way that I've not seen in any other book. The introduction and contrast of the Groovy, Scala and Clojure JVM languages I also thought was done well. Some aspects of the book are now dated but it's still worthwhile skimming over for a historical context of how the platform has developed. If you're new to programming and new to Java development however this probably isn't the right book to start with.
