Apache Maven is an open-source tool used for project management and comprehension. The tool is based on the project object model (POM) concept. With Apache <ave, you can easily manage all the aspects of a project including the build, documentation and reporting from a central point. In addition to that, you can use it to create sites and upload the build results. This is a very vital tool as it automates the process of creating an initial folder of Java apps, compiling, testing, packaging and deployment of products.

Maven enables developers to comprehend a full development cycle and state in the shortest time possible. This in turn makes the build process easier, improves development practices and provides quality project information.

The amazing features associated with Apache Maven are:

  • It is easy to set up and use
  • It can work with multiple projects simultaneously
  • Instant access to new features and improvements with minimal or no configs required.
  • It is highly extensive. You can write the desired plugins in Java and other languages.
  • It encourages the use of a central repository for JARs and the other involved dependencies.
  • It has a large and active community and libraries to use

This guide will provide the common commands involved when Using Apache Maven with examples where necessary.

Installing Apache Maven

Apache Maven can be installed on your system by following the guides available on our page:

To verify the installation, run:

$ mvn -version
Apache Maven 3.9.4 (dfbb324ad4a7c8fb0bf182e6d91b0ae20e3d2dd9)
Maven home: /opt/maven
Java version: 11.0.20.1, vendor: Ubuntu, runtime: /usr/lib/jvm/java-11-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.15.0-71-generic", arch: "amd64", family: "unix"

Using Apache Maven – Commands with Examples

After installing Apache Maven, you can proceed and use it as desired. Here is a list of the commonly used Apache Maven commands with examples:

mvn compile

This command is used to compile the main source code of the project located in src/main/java of the project. The command compiles all the Java files in the main directory. The command does not perform any tasks beyond the compile phase.

mvn compile

Sample Output:

[INFO] Compiling 1 source file with javac [debug target 1.8] to target/classes
[WARNING] bootstrap class path not set in conjunction with -source 8
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.363 s
[INFO] Finished at: 2023-09-18T13:18:32+03:00
[INFO] ------------------------------------------------------------------------

mvn compiler:compile

This command is used when compiling the Java source codes for a Maven project. It tells Maven to use the maven-compiler-plugin when compiling the code. Here, the behaviour of the compiler can be customized in the pom.xml file. You can specify options such as the source and target Java versions, encoding etc. To use it, run:

$ mvn compiler:compile
[INFO] 
[INFO] ----------------------< com.mycompany.app:my-app >----------------------
[INFO] Building my-app 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- compiler:3.11.0:compile (default-cli) @ my-app ---
[INFO] Changes detected - recompiling the module! :input tree
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 1 source file with javac [debug target 1.8] to target/classes
[WARNING] bootstrap class path not set in conjunction with -source 8
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.435 s
[INFO] Finished at: 2023-09-18T13:19:02+03:00
[INFO] ------------------------------------------------------------------------

mvn compiler:testCompile

This command is used to compile the test classes of the Maven project.

$ mvn compiler:testCompile
[INFO] Scanning for projects...
[INFO] 
[INFO] ----------------------< com.mycompany.app:my-app >----------------------
[INFO] Building my-app 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- compiler:3.11.0:testCompile (default-cli) @ my-app ---
[INFO] Changes detected - recompiling the module! :source
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 1 source file with javac [debug target 1.8] to target/test-classes
[WARNING] bootstrap class path not set in conjunction with -source 8
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.614 s
[INFO] Finished at: 2023-09-18T13:19:38+03:00
[INFO] ------------------------------------------------------------------------

mvn package

It is used when building the Maven project into a JAR, WAR etc. To use it, execute the command:

mvn package

Sample output:

[INFO] Building jar: /home/thor/mvn-projects/my-app/target/my-app-1.0-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.826 s
[INFO] Finished at: 2023-09-18T13:20:05+03:00
[INFO] ------------------------------------------------------------------------

Once complete, you will see the location of the JAR file printed. The command executes the compile, testCompile and test before proceeding with the build.

mvn install

This command will build and install the JAR, WAR, pom.xml etc project files to the local repo. To use it, run:

mvn install

Sample Output:

[INFO] Installing /home/thor/mvn-projects/my-app/pom.xml to /home/thor/.m2/repository/com/mycompany/app/my-app/1.0-SNAPSHOT/my-app-1.0-SNAPSHOT.pom
[INFO] Installing /home/thor/mvn-projects/my-app/target/my-app-1.0-SNAPSHOT.jar to /home/thor/.m2/repository/com/mycompany/app/my-app/1.0-SNAPSHOT/my-app-1.0-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.838 s
[INFO] Finished at: 2023-09-18T13:21:06+03:00
[INFO] ------------------------------------------------------------------------

mvn deploy

It deploys the artefacts to a remote repository configured in the pom.xmlfile under with distributionManagement tag. To provide authentication details, include them in the settings.xml file.

mvn deploy

mvn validate

It is used to validate and ensure that all the settings and the required information are correct for the Maven project.

$ mvn validate
[INFO] Scanning for projects...
[INFO] 
[INFO] ----------------------< com.mycompany.app:my-app >----------------------
[INFO] Building my-app 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.196 s
[INFO] Finished at: 2023-09-18T13:21:59+03:00
[INFO] ------------------------------------------------------------------------

mvn dependency:tree

Used to display the dependency tree on your Maven project.

mvn dependency:tree

Sample Output:

[INFO] \- junit:junit:jar:3.8.1:test
[INFO] |  +- org.apiguardian:apiguardian-api:jar:1.0.0:test
[INFO] |  +- org.junit.platform:junit-platform-launcher:jar:1.2.0:test
[INFO] |  \- org.junit.platform:junit-platform-suite-api:jar:1.2.0:test
[INFO] |     \- org.junit.platform:junit-platform-commons:jar:1.2.0:test
[INFO] +- org.junit.jupiter:junit-jupiter-engine:jar:5.2.0:test
.....

This command can be used to locate the unused dependencies and remove them from your pom.xml file.

mvn archetype:generate

This command is useful when generating a skeleton of the project. It generates the JAR, web apps, maven sites and many others.

mvn archetype:generate

You can also use the command along with all the required flags. For example

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

mvn site:site

This command is used to create the site of the project. To use the command, run:

mvn site:site

There will be HTML files generated with information related to your project in the site directory. To view them access the below directory on your project.

$ ls target/site/
css/                    dependency-info.html    index.html              plugins.html            summary.html            
dependencies.html       images/                 plugin-management.html  project-info.html

mvn test

This is used when running the test cases for your Maven project. For example:

$ mvn test
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.mycompany.app.AppTest
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.036 s -- in com.mycompany.app.AppTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.231 s
[INFO] Finished at: 2023-09-18T13:35:08+03:00
[INFO] ------------------------------------------------------------------------

mvn verify

This command is used when you need to verify that the quality criteria are met. It runs the test cases and checks to ensure all is okay.

mvn verify

Sample Output:

INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.mycompany.app.AppTest
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.039 s -- in com.mycompany.app.AppTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] 
[INFO] --- jar:3.3.0:jar (default-jar) @ my-app ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.564 s
[INFO] Finished at: 2023-09-18T13:35:56+03:00
[INFO] ------------------------------------------------------------------------

mvn Clean

This command is used when deleting the Maven project. It cleans and deletes the target directory. To use it, switch to the Maven directory and issue:

$ mvn clean
[INFO] Scanning for projects...
[INFO] 
[INFO] ----------------------< com.mycompany.app:my-app >----------------------
[INFO] Building my-app 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- clean:3.2.0:clean (default-clean) @ my-app ---
[INFO] Deleting /home/thor/mvn-projects/my-app/target
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.554 s
[INFO] Finished at: 2023-09-18T13:36:22+03:00
[INFO] ------------------------------------------------------------------------

How to use Maven Options

Maven allows the usage of several options. To view the list of the available options use:

$ mvn -help
usage: mvn [options] [<goal(s)>] [<phase(s)>]

Options:
 -am,--also-make                        If project list is specified, also
                                        build projects required by the
                                        list
 -amd,--also-make-dependents            If project list is specified, also
                                        build projects that depend on
                                        projects on the list
 -B,--batch-mode                        Run in non-interactive (batch)
                                        mode (disables output color)
 -b,--builder <arg>                     The id of the build strategy to
                                        use
 -C,--strict-checksums                  Fail the build if checksums don't
                                        match
 -c,--lax-checksums                     Warn if checksums don't match
    --color <arg>                       Defines the color mode of the
                                        output. Supported are 'auto',
                                        'always', 'never'.
 -cpu,--check-plugin-updates            Ineffective, only kept for
                                        backward compatibility
 -D,--define <arg>                      Define a user property
 -e,--errors                            Produce execution error messages
 -emp,--encrypt-master-password <arg>   Encrypt master security password
 -ep,--encrypt-password <arg>           Encrypt server password
 -f,--file <arg>                        Force the use of an alternate POM
                                        file (or directory with pom.xml)
 -fae,--fail-at-end                     Only fail the build afterwards;
                                        allow all non-impacted builds to
                                        continue
......

Below are some of the most commonly used maven options:

mvn -o package

This command is used to run the maven build command in the offline mode. This command is only used when all the required JAR files are already downloaded and available in the local repo.

mvn -o package

mvn -q package

This runs the build process in a quiet mode, only the results and errors are provided for this.

mvn -q package

mvn -f dir/pom.xml package

The command is used when building a project from another path. You need to specify the location of the pom.xml file:

mvn -f dir/pom.xml package

mvn -T 4 clean install

The command is used to run parallels Maven builds with the provided count. This command can be used to reduce the build time since the modules can be built simultaneously. For example:

mvn -T 4 clean install

mvn -X package

The command is used to display the Maven version and run the build in debug mode. Here, all the messages are printed.

mvn -X package

Sample Output:

Apache Maven 3.9.4 (dfbb324ad4a7c8fb0bf182e6d91b0ae20e3d2dd9)
Maven home: /opt/maven
Java version: 11.0.20.1, vendor: Ubuntu, runtime: /usr/lib/jvm/java-11-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.15.0-71-generic", arch: "amd64", family: "unix"
...
INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.832 s
[INFO] Finished at: 2023-09-18T13:38:09+03:00
[INFO] ------------------------------------------------------------------------
[DEBUG] Shutting down adapter factory; available factories [file-lock, rwlock-local, semaphore-local, noop]; available name mappers [discriminating, file-gav, file-hgav, file-static, gav, static]
[DEBUG] Shutting down 'file-lock' factory
[DEBUG] Shutting down 'rwlock-local' factory
[DEBUG] Shutting down 'semaphore-local' factory
[DEBUG] Shutting down 'noop' factory

mvn -V package

The command prints the Maven version and then proceeds with the build process.

mvn -V package
##OR
mvn -v;mvn package

mvn -DskipTests package

The option is used to skip the tests during the build process:

mvn -DskipTests package
##OR
mvn -Dmaven.test.skip=true package

Conclusion

This guide can be used as a reference material when dealing with the Apache Maven project. We have provided some of the commonly used Maven commands and the example usage. I hope this was helpful.

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