Ask HN: Tools for (re)learning Java 15 years ago
One of the biggest changes in the past 7 years is the rise in popularity of Unit Testing.
It light of that, I recommend picking up Robert C. Martin's clean code - while it isn't specifically about the Java language (though lots of the examples are in Java) it will refresh you on how to write good Object Oriented systems that are easily testable.
After years of reading procedural Java code, its clear that syntax is not enough...