Image from Amazon Title: The Java Module System
Amazon wrote:Java's much-awaited "Project Jigsaw" is finally here! Java 11 includes a built-in modularity framework, and The Java Module System is your guide to discovering it. In this new book, you'll learn how the module system improves reliability and maintainability, and how it can be used to reduce tight coupling of system components.
Up front: I'm a bit biased here as I was the Technical Development Editor and contributed a bit to this book. However, it is an excellent book.
When I started reading, I wondered how one could write a whole book about the Java Module System. Well you can. This book reminded me a little of the O'Reilly Regular Expression book. If you want to understand the topic just enough to get started, you can read just a little. If you want to understand it in depth, you can read the whole book.
I really liked the examples and migration strategies in this book. I didn't know much about the module system starting out. By the time I finished the book, I knew a good amount. Then I didn't use it and forgot.
This year, I took both OCP Java certification exams. As both covered modules, I used this book to study the topic. It came back right away and I am recommending chapters in this book to those studying for the certification. (Until study guides come out.) Conveniently, Manning allows buying parts of a book.
If you want to learn about modules rather than just pass the cert, you should buy the whole book though! You'll learn a lot; even in the appendixes.