Book Image

Modular Programming in Java 9

By : Koushik Srinivas Kothagal
Book Image

Modular Programming in Java 9

By: Koushik Srinivas Kothagal

Overview of this book

The Java 9 module system is an important addition to the language that affects the way we design, write, and organize code and libraries in Java. It provides a new way to achieve maintainable code by the encapsulation of Java types, as well as a way to write better libraries that have clear interfaces. Effectively using the module system requires an understanding of how modules work and what the best practices of creating modules are. This book will give you step-by-step instructions to create new modules as well as migrate code from earlier versions of Java to the Java 9 module system. You'll be working on a fully modular sample application and add features to it as you learn about Java modules. You'll learn how to create module definitions, setup inter-module dependencies, and use the built-in modules from the modular JDK. You will also learn about module resolution and how to use jlink to generate custom runtime images. We will end our journey by taking a look at the road ahead. You will learn some powerful best practices that will help you as you start building modular applications. You will also learn how to upgrade an existing Java 8 codebase to Java 9, handle issues with libraries, and how to test Java 9 applications.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Handling larger codebases


The sample application we modularized is very simple and not a representation of most real-world applications. Here are a couple of characteristics in which most applications differ:

  • They have a broader code base that spans multiple projects. These projects may reside in different source locations and may be hooked to a build system. The build of the main application then gathers the right dependencies together to form the final application build.
  • They have many more framework dependencies that have more complex needs. Frameworks such as Spring or Hibernate require access to your application code to do reflection. They might scan your classes for annotations and do various things such as dependency injection and object-relational mapping. In that sense, it is not just your application code that needs access to libraries as automatic modules; even such automatic modules would need access to your application code.

Given such a large Java 8 code base, how do you even...