August 2026
Beginner to intermediate
538 pages
14h 40m
English
Content preview from Java in a Nutshell, 9th Edition
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Chapter 14. Java Platform Modules
In this chapter, we will provide a basic introduction to the Java Platform Modules System (JPMS). However, this is a large, complex subject—interested readers may well require a more in-depth reference, such as Java 9 Modularity by Sander Mak and Paul Bakker (O’Reilly).
Modules, a relatively advanced feature, are primarily about packaging and deploying entire applications and their dependencies. They were added to the platform roughly 20 years after the first version of Java and so can be seen as mostly orthogonal to the rest of the language syntax.
Java’s strong promotion of backward compatibility also plays a role here, as non-modular applications must continue to run. This has led the architects and stewards of the Java platform to adopt a pragmatic view of the necessity for teams to adopt modules for existing code. This is perhaps best expressed by this quote from Oracle’s Java Platform Architect:
There is no need to switch to modules.
There has never been a need to switch to modules.
Java 9 and later releases support traditional JAR files on the traditional classpath, via the concept of the unnamed module, and will likely do so until the heat death of the universe.
Whether to start using modules is entirely up to you.
Due to the advanced nature of modules, this chapter assumes you are familiar with a modern Java build tool, such as Gradle or Maven.
If you are new to Java, you can safely ignore references to those tools and ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.