java modules maven

Catherine 181 Published: 08/02/2024

java modules maven

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Java modules are a feature introduced in Java 9 that allows for better encapsulation and reuse of code. A module is a set of related classes, interfaces, and other resources packaged together as a single unit.

In Maven, you can create modules by creating separate directories within your project's directory structure. Each directory should contain its own module-info.java file, which defines the module's name and the packages that it contains.

Here are some basic steps to create a Java module in Maven:

Create a new directory for your module: 
mkdir my-module
Create a module-info.java file within this directory: 
cd my-module

touch module-info.java
In the module-info.java file, define your module's name and the packages that it contains: 
@MODULE

public class MyModule {


public requires public "org.example";


public provides org.example.MyClass;


}
Create a separate directory for each package that you want to include in your module: 
mkdir org/example
Place your Java source files within these directories. In your pom.xml file, define the modules and their dependencies: 
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">


4.0.0


com.example


my-project


1.0-SNAPSHOT


jar


org.example


my-module


1.0-SNAPSHOT


org.apache.maven.plugins


maven-compiler-plugin


1.8

1.8


my-module
Build and run your module: 
mvn package

That's it! You've successfully created a Java module in Maven.

Note that you can have multiple modules within a single project, each with its own dependencies and requirements.

java modules vs maven modules

Java modules and Maven modules are two distinct concepts that often get confused with each other. While both are used to organize and manage code, they serve different purposes and have unique characteristics.

Maven Modules

In Maven, a module is a logical unit of functionality that can be independently compiled, tested, and deployed. Maven modules are typically represented as a single Java package or a collection of packages that provide a specific feature or functionality. Each module has its own pom.xml file, which contains metadata about the module, such as its name, dependencies, and build configuration.

Maven modules are primarily used to manage dependencies between projects. When you create a Maven module, you can specify the dependencies required by the module using the <dependencies> tag in the pom.xml file. This allows you to easily reuse code from other projects or libraries.

Java Modules

In Java, a module is a collection of related classes, interfaces, and modules that are compiled together into a single unit called a JAR (Java ARchive) file. Java modules were introduced in Java 9 as part of the Java Platform Module System (JPMS).

A Java module is typically represented by a module-info.java file that contains metadata about the module, such as its name, requires clauses for dependencies, and exports clauses for exposing APIs. Java modules are used to organize code into logical units that can be independently compiled, tested, and deployed.

Key Differences

The main differences between Maven modules and Java modules are:

Purpose: Maven modules focus on managing dependencies between projects, while Java modules focus on organizing and compiling code. Structure: Maven modules have a single pom.xml file, whereas Java modules have a separate module-info.java file that contains metadata about the module. Compilation: Maven modules do not require explicit compilation or packaging of code. In contrast, Java modules require explicit compilation and packaging into a JAR file.

When to Use Each

Maven modules are typically used when you need to manage dependencies between multiple projects or reuse code from other libraries. For example, if you have a project that depends on several other Maven projects or libraries, you would use Maven modules to manage these dependencies.

Java modules are typically used when you want to organize and compile code for a specific feature or functionality within a single project. For example, if you're building a large application with multiple features, each feature might be represented as a separate Java module that can be independently compiled, tested, and deployed.

In summary, Maven modules and Java modules serve different purposes and have distinct characteristics. While both are used to organize and manage code, Maven modules focus on managing dependencies between projects, while Java modules focus on organizing and compiling code for specific features or functionalities within a single project.

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