Java Platform Module System (JPMS) and Project Jigsaw are two of the most significant features in Java SE 9 that have revolutionized how developers write and manage large-scale applications. Modularity is an essential aspect of modern software development, and it has become increasingly important for developers to create modular applications that are easy to maintain, update, and scale. In this article, we will provide a practical guide to using JPMS and Project Jigsaw to develop modular applications in Java.

Understanding Java Modules: Key Concepts and Benefits

Before we dive into using JPMS and Project Jigsaw, it’s essential to have a good understanding of the key concepts and benefits of Java modules. A module is a self-contained unit of code that encapsulates a set of related functionalities. Modules provide a way to organize code into logical groupings, making it easier to manage and reuse code across multiple applications. Some of the benefits of modular development include better code organization, improved code reusability, and easier maintenance of large-scale applications.

Getting Started with Project Jigsaw: Step-by-Step Guide

To get started with Project Jigsaw, you’ll need to have Java 9 or above installed on your machine. Once you have Java 9 installed, you can begin creating your first Java module. The first step is to create a new module-info.java file in your project’s root directory. The module-info.java file defines the module’s name, dependencies, and exports.

module com.example.myapp {
    requires java.logging;
    exports com.example.myapp;
}

In the example above, we define a module named "com.example.myapp" that depends on the Java Logging API and exports the package "com.example.myapp." The next step is to compile the module using the javac command and create a module JAR file using the jar command.

javac -d mods/com.example.myapp src/com.example.myapp/module-info.java src/com.example.myapp/MyApp.java
jar --create --file=mlib/com.example.myapp.jar --main-class=com.example.myapp.MyApp -C mods/com.example.myapp .

Best Practices for Modular Development: Tips and Tricks

Modular development requires a different approach than traditional monolithic development. Here are some best practices for modular development:

• Use descriptive and meaningful module names that accurately reflect the module’s functionality.
• Avoid circular dependencies between modules to prevent runtime errors and improve code maintainability.
• Keep modules small and focused on a specific set of functionalities for easy reuse and maintenance.
• Use the "exports" directive carefully to control access to module APIs and prevent unauthorized access.
• Use the "requires transitive" directive to automatically propagate module dependencies to dependent modules.
• Use the "open" directive to allow reflective access to specific packages in a module.

In conclusion, modular development using JPMS and Project Jigsaw provides a powerful way to organize and manage large-scale applications in Java. It offers many benefits such as improved code organization, reusability, and maintenance. This article has provided a practical guide to using JPMS and Project Jigsaw, highlighting key concepts and benefits, step-by-step guide, and best practices for modular development. By following these guidelines, developers can create modular applications that are easy to manage, maintain, and scale.