Maven POM

Maven Project Object Model (POM) is an XML file that contains information about the project and configuration details used by Maven to build the project.

Introduction

Maven is a widely used build tool that simplifies the building, testing, and deployment of Java projects. Maven manages project dependencies, builds the project and creates documentation.

A POM file acts as the basic unit of work in Maven. This file contains a description of the project, its dependencies, and how it should be built.

POM Structure

The POM file is an XML file that contains a hierarchy of elements, each of which corresponds to an aspect of the project. The major elements of the POM file are:

• project: The root element of the POM file.
• modelVersion: The version of the POM file format being used.
• groupId: A unique identifier for the project's module or organization.
• artifactId: A unique identifier for the project's library.
• version: The version of the project.
• dependencies: The list of third-party dependencies on which the project depends.

Here's an example of a POM file:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

Using the POM

The POM is used by Maven to build the project and manage its dependencies. When you run a command like mvn package, Maven uses the information in the POM file to download all the necessary dependencies, compile the code, and create an executable JAR file.

You can customize the build process by modifying the POM file. For example, you can specify build plugins, set the compiler version, and configure Maven plugins.

Conclusion

The Maven POM is an essential file that contains configuration details for a Maven project. It serves as a blueprint for the project build and is used by Maven to manage dependencies and build the project. Understanding the basics of the POM file is crucial for any Java developer who's working with Maven.