Maven is used to manage dependencies and the process of compiling and executing a Java project.

Project Creation

The project is created using the archetype quickstart and the command

mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.5 -DinteractiveMode=false

The project folder will then be created, in this case my-app, which will include the file pom.xml:

<?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 http://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>

 <name>my-app</name>
 <!-- FIXME change it to the project's website -->
 <url>http://www.example.com</url>

 <properties>
   <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   <maven.compiler.release>17</maven.compiler.release>
 </properties>

 <dependencyManagement>
   <dependencies>
     <dependency>
       <groupId>org.junit</groupId>
       <artifactId>junit-bom</artifactId>
       <version>5.11.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
   </dependencies>
 </dependencyManagement>

 <dependencies>
   <dependency>
     <groupId>org.junit.jupiter</groupId>
     <artifactId>junit-jupiter-api</artifactId>
     <scope>test</scope>
   </dependency>
   <!-- Optionally: parameterized tests support -->
   <dependency>
     <groupId>org.junit.jupiter</groupId>
     <artifactId>junit-jupiter-params</artifactId>
     <scope>test</scope>
   </dependency>
 </dependencies>

 <build>
   <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
   ... Various helpful plugins
   </pluginManagement>
 </build>
</project>

Where the attributes are defined within the object element:

• modelVersion: the version of POM we are using. This number rarely changes;
• groupId: a unique identifier used to define the company that created the project. It is the domain name of the organization;
• artifactId: the name of the project’s main program. Typically, this is a <artifactId>-<version>.jar file (it can also have extensions other than .jar);
• version: this is the version of the artifact being created in this project. If you have SNAPSHOT in the version, it means that the project is under development;
• name: this is the name under which the project will be known. It is used to generate documentation;
• url: indicates the project website;
• properties: indicates various values that are accessible within the entire POM;
• dependencies: lists all the project dependencies;
• build: this element is responsible for defining the project structure and managing the various plugins.

The structure of the project will be as follows::

my-app
├── pom.xml
└── src
   ├── main
   │   └── java
   │       └── com
   │           └── mycompany
   │               └── app
   │                   └── App.java
   └── test
       └── java
           └── com
               └── mycompany
                   └── app
                       └── AppTest.java

Project compilation

The project is compiled using the command:

mvn compile

After downloading all plugins and dependencies, if they are not already present in the system, it will place the compiled files in ${project.basedir}/target/classes.

Run unit tests

To run the unit tests, use the command:

mvn test

Maven will then download development dependencies, in addition to those required for the project, and recompile the main code to run the tests, including all changes made since the last mvn compile. If you only want to compile without running the tests, the command is:

mvn test-compile

Create a JAR and install it locally

The JAR file is created using the command:

mvn package

The file will be placed in the ${project.basedir}/target directory. To install the project in the local repository, located in $HOME/.m2/repository by default, you must execute:

mvn install

To generate the project website, which will be located in ${project.basedir}/target/site, use the command:

mvn site

And to clean up all files generated from the source, use the command:

mvn clean