Modern Java Recipes

Preface

Modern Java

Sometimes it’s hard to believe that a language with literally 20 years of backward compatibility could change so drastically. Prior to the release of Java SE 8 in March of 2014,¹ for all of its success as the definitive server-side programming language, Java had acquired the reputation of being “the COBOL of the 21st century.” It was stable, pervasive, and solidly focused on performance. Changes came slowly when they came at all, and companies felt little urgency to upgrade when new versions became available.

That all changed when Java SE 8 was released. Java SE 8 included “Project Lambda,” the major innovation that introduced functional programming concepts into what was arguably the world’s leading object-oriented language. Lambda expressions, method references, and streams fundamentally changed the idioms of the language, and developers have been trying to catch up ever since.

The attitude of this book is not to judge whether the changes are good or bad or could have been done differently. The goal here is to say, “this is what we have, and this is how you use it to get your job done.” That’s why this book is designed as a recipes book. It’s all about what you need to do, and how the new features in Java help you do it.

That said, there are a lot of advantages to the new programming model, once you get used to them. Functional code tends to be simpler and easier to both write and understand. The functional approach favors immutability, which makes writing ...