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Jan 2, 2024 · Java Module System provides an additional layer of encapsulation to our programs as we can specify which package can be utilized by the modules, and which modules could have entry to to them. Before entering into the exclusive types of modules in Java, we will first learn the differences among applications and modules.
- What Is A Module?
- Introduction to Java Platform Module System
- Conclusion
In any programming language, modules are (package-like) artifacts containing code, with metadata describing the module and its relation to other modules. Ideally, these artifacts are recognizable from compile-time all the way through runtime. Any application generally is a combination of multiple modules which work together to perform the business ...
2.1. The Problem
Before Java 9, we had ‘packages‘ to group related classes as per business capabilities. Along with packages, we had ‘access modifiers‘ to control what would be visible and what would be hidden to other classes or packages. It has been working great so far. But, explicit dependencies are where things start to fall apart. In Java, dependencies are declared with ‘import‘ statements; but they are strictly ‘compile time’ constructs. Once code is compiled, there is no mechanism to state its runtime...
2.2. How does JPMS Solve the Problem?
With new Java 9 modules, we will have better capability to write well-structured applications. This enhancement is divided into two areas: 1. Modularize the JDK itself. 2. Offer a module system for other applications to use. In Java 9, modules help us in encapsulating packages and managing dependencies. So typically, 1. a class is a container of fields and methods 2. a package is a container of classes and interfaces 3. a module is a container of packages
2.3. Difference between modular and non-modular code
You will not feel any significant difference between regularcode and modular code if you don’t know the specific things to look for. e.g. 1. A module is typically just a jar file that has a module-info.classfile at the root. 2. To use a module, include the jar file into modulepath instead of the classpath. A modular jar file added to classpath is normal jar file and module-info.classfile will be ignored.
Modular applications have many advantages, which you appreciate even more when you come across applications having a non-modular codebase. You must have heard terms like “spaghetti architecture” or “messy monolith“. Modularity is not a silver bullet, but it is an architectural principle that can prevent these problems to a high degree when applied ...
Dec 15, 2018 · This page will walk through Java 9 Module Example. A Module is a set of packages designed for reuse. In Java 9, Java programs are Modules. Java Module is the main feature introduced in Java 9 release. In Java we have classes, packages and now modules, too. Before Java 9 module, Java programs are packages.
Module Declarations. At the core of each module is the module declaration, a file with the name module-info.java that defines all properties of a module. As an example, here's the one for java.sql, the platform module that defines the JDBC API:
Jun 11, 2024 · Java 9 introduces a new level of abstraction above packages, formally known as the Java Platform Module System (JPMS), or “Modules” for short. In this tutorial, we’ll go through the new system and discuss its various aspects.
- Christopher Franklin
Oct 3, 2017 · Learn all the module system basics in this tutorial: how to declare modules with module-info.java, compile, package, and launch them and what role the module path and readability graph play.
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Sep 11, 2018 · In this article we will learn the most important feature of Java 9 – “Java 9 Modules“. We will cover everything like why we need modules, what is a module, how to create and use Modules in Java.
