Introduction
Maven is a build-automation tool designed to provide a comprehensive and easy-to-use way of developing Java applications. It uses a POM (Project Object Model) approach to create a standardized development environment for multiple teams. It also handles project dependencies, plugins, reports, and other aspects of the build process.
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Maven's primary goal is to allow a developer to comprehend the complete state of a development effort in the shortest period of time. To achieve this goal, Maven deals with several areas of concern:
Making the build process easy: Maven simplifies the build process by providing a uniform way of building any Java-based project. It also shields developers from many details of the underlying mechanisms.
Providing a uniform build system: Maven builds a project using its POM and a set of plugins. Once you familiarize yourself with one Maven project, you know how all Maven projects build.
Providing quality project information: Maven provides useful project information that is partly taken from the POM and partly generated from the project's sources. For example, Maven can provide change logs, cross-referenced sources, mailing lists, dependencies, test reports, code analysis reports, etc.
Encouraging better development practices: Maven aims to gather current principles for best practices development and make it easy to guide a project in that direction. For example, specification, execution, and reporting of unit tests are part of the normal build cycle using Maven.
In this article, we will show you how to download and install Maven on your system, how to use some common Maven commands, and how to troubleshoot some common Maven errors.
Downloading and installing Maven
Prerequisites
To install Maven on your system, you need the following:
A system running Windows, Linux, or Mac OS X.
A working Internet connection.
Access to an account with administrator privileges.
Access to the command prompt or terminal.
A copy of Java installed and ready to use, with the JAVA_HOME environment variable set up (learn how to set up the JAVA_HOME environment variable in our ).
Installation steps
To install Maven on your system, follow these steps:
Visit the and download the version of Maven you want to install. The Files section contains the archives of the latest version. Access earlier versions using the archives link in the Previous Releases section.
Extract the distribution archive in any directory and add the bin directory with the mvn command to the PATH environment variable. Alternatively use your preferred archive extraction tool.
Add a system variable named MAVEN_HOME and point it to the root Maven directory. Also add %MAVEN_HOME%\bin to the PATH variable.
VerificationVerification
To verify that Maven is installed correctly, open a new command prompt or terminal window and run the following command:
mvn --version
You should see output similar to this:
Apache Maven 3.8.4 (9b656c72d54e8b2b6a976121d22377b6a53c422e) Maven home: C:\Program Files\apache-maven-3.8.4 Java version: 11.0.13, vendor: Oracle Corporation, runtime: C:\Program Files\Java\jdk-11.0.13 Default locale: en_US, platform encoding: Cp1252 OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"
If you see a message like this, congratulations! You have successfully installed Maven on your system. If you see an error message or no output at all, check your installation steps and environment variables again.
Using Maven commands
Basic commands
Maven provides a set of basic commands that allow you to perform common tasks such as cleaning, compiling, testing, packaging, and installing your project. Here are some of the most frequently used Maven commands:
mvn clean: This command deletes the target directory with all the build data created by Maven during the build process.
mvn compile: This command compiles the source code of your project and puts the compiled classes in the target/classes directory.
mvn test: This command runs the unit tests of your project using a suitable testing framework such as JUnit or TestNG. It also generates test reports in the target/surefire-reports directory.
mvn package: This command takes the compiled code and packages it into a distributable format such as a JAR, WAR, or EAR file. It also runs the unit tests before packaging.
mvn install: This command installs the packaged artifact into the local repository, which can be used as a dependency in other projects locally.
You can also combine these commands in a single execution by using a space as a separator. For example, mvn clean install will first clean the project and then install it.
How to download and install Apache Maven on Windows
Download Maven zip file and extract it
Add MAVEN_HOME system variable and directory in PATH variable
Verify Maven installation with mvn -v command
Download Apache Maven 3.9.2 latest release
Maven system requirements and supported JDK versions
How to use Maven toolchains to build against different JDKs
How to verify the signature of the Maven release bundles
How to download Maven source code from source repository
How to build Maven from source code
How to update Maven to the latest version
How to uninstall Maven from Windows
How to download and install Maven on Linux
How to download and install Maven on Mac OS X
How to configure Maven settings.xml file
How to create a Maven project using mvn archetype:generate command
How to run a Maven project using mvn package or mvn install command
How to test a Maven project using mvn test command
How to clean a Maven project using mvn clean command
How to skip tests in Maven using -DskipTests option
How to add dependencies to a Maven project using pom.xml file
How to use Maven repositories to manage dependencies
How to create a custom Maven repository using Nexus or Artifactory
How to use Maven plugins to enhance the build process
How to create a custom Maven plugin using Mojo API
How to use Maven profiles to customize the build for different environments
How to use Maven properties to parameterize the build configuration
How to use Maven filters to replace placeholders in resources files
How to use Maven resources plugin to copy and filter resources files
How to use Maven compiler plugin to specify the source and target Java version
How to use Maven surefire plugin to run unit tests and generate reports
How to use Maven failsafe plugin to run integration tests and generate reports
How to use Maven jacoco plugin to measure code coverage and generate reports
How to use Maven checkstyle plugin to enforce coding standards and generate reports
How to use Maven findbugs plugin to detect bugs and generate reports
How to use Maven PMD plugin to detect code quality issues and generate reports
How to use Maven sonar plugin to perform code analysis and generate reports
How to use Maven site plugin to generate project documentation and reports
How to use Maven deploy plugin to deploy artifacts to a remote repository or server
How to use Maven release plugin to automate the release process of a project
How to use Maven assembly plugin to create a single executable jar file with dependencies
How to use Maven shade plugin to create an uber-jar file with shaded dependencies
How to use Maven war plugin to create a web application archive file for deployment
How to use Maven ear plugin to create an enterprise application archive file for deployment
How to use Maven ejb plugin to create an enterprise Java bean archive file for deployment
How to use Maven spring boot plugin to create a self-contained executable jar file for spring boot applications
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Advanced commands
Maven also provides some advanced commands that allow you to perform more complex tasks such as generating project skeletons, analyzing dependencies, creating documentation, and deploying artifacts to remote repositories. Here are some of the most useful Maven commands for advanced users:
mvn archetype:generate: This command creates a new project from a template called an archetype. An archetype is a predefined project structure that follows certain conventions and best practices. You can choose from a list of available archetypes or create your own.
mvn dependency:tree: This command displays the dependency tree of your project, showing all the direct and transitive dependencies that your project depends on. It also shows the scope and version of each dependency.
mvn site: This command generates a website for your project that contains various information such as project description, license, developers, mailing lists, issue tracking, source code management, reports, etc. The website is generated in the target/site directory by default.
mvn deploy: This command deploys the packaged artifact to a remote repository for sharing with other developers and projects. You need to configure the repository details in your POM or settings.xml file before using this command.
Command-line options
Maven also supports several command-line options that modify the behavior of Maven commands. You can use these options to customize your build process according to your needs and preferences. Here are some of the most common Maven command-line options:
-Dname=value: This option sets a system property with the given name and value. You can use this option to pass parameters to your Maven plugins or override some configuration values in your POM.
-T nC: This option enables parallel builds using multiple threads. You can specify the number of threads to use by appending a number followed by C (for cores) or W (for work units). For example, -T 4C will use four threads per core.
-X: This option enables debug mode, which prints additional information about the build process such as plugin executions , plugin configurations, dependency resolutions, etc. This option is useful for debugging and troubleshooting Maven issues.
-q: This option enables quiet mode, which suppresses most of the output from Maven commands. Only errors and warnings are displayed in this mode. This option is useful for minimizing the noise in your build logs.
-U: This option forces Maven to update the dependencies from the remote repositories. This option is useful for ensuring that you have the latest versions of your dependencies.
-o: This option forces Maven to work in offline mode, which means that it will not attempt to connect to any remote repositories. This option is useful for working with local dependencies or when you have network issues.
-f: This option specifies an alternate POM file to use for the build. You can use this option to build a project with a different POM than the default one.
-P: This option activates one or more profiles in your POM or settings.xml file. A profile is a set of configuration values that can be used to customize your build for different environments or scenarios. You can use this option to switch between different profiles.
Troubleshooting Maven errors
Compiler version problems
One of the most common Maven errors is related to the compiler version used by Maven to compile your project. If you see an error message like this:
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project my-app: Fatal error compiling: invalid target release: 11 -> [Help 1]
It means that Maven is trying to compile your project with a Java version that is not compatible with the target release specified in your POM. For example, if you have this in your POM:
<properties> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties>
It means that you want to compile your project with Java 11, but Maven is using a lower version of Java. To fix this error, you need to make sure that you have Java 11 installed on your system and that the JAVA_HOME environment variable points to it. You can also specify the compiler version explicitly in your POM by adding this:
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.1</version> <configuration> <source>11</source> <target>11</target> <compilerVersion>11</compilerVersion> </configuration> </plugin>
Project start problems
Another common Maven error is related to the project start or import process. If you see an error message like this:
[ERROR] The goal you specified requires a project to execute but there is no POM in this directory (C:\Users\user\my-app). Please verify you invoked Maven from the correct directory. -> [Help 1]
It means that Maven cannot find a POM file in the current directory. A POM file is essential for Maven to understand the structure and configuration of your project. To fix this error, you need to make sure that you are in the right directory where your POM file is located, or specify the path to your POM file using the -f option.
If you see an error message like this:
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-archetype-plugin:3.2.0:generate (default-cli) on project standalone-pom: The desired archetype does not exist (org.apache.maven.archetypes:maven-archetype-quickstart:1.0) -> [Help 1]
It means that Maven cannot find the archetype that you want to use to generate a new project. An archetype is a template that provides a predefined project structure and configuration. To fix this error, you need to make sure that you have specified the correct archetype groupId, artifactId, and version, or choose from a list of available archetypes using the interactive mode.
Other common errors
Maven can Maven can also encounter other errors that are related to dependency conflicts, plugin failures, network issues, etc. These errors can vary depending on the specific situation and configuration of your project. However, there are some general steps that you can take to troubleshoot and resolve these errors:
Read the error message carefully and try to understand what it means and what caused it. Sometimes, the error message will provide a hint or a suggestion on how to fix it.
Check the Maven documentation and online resources for more information and possible solutions. You can use the [Help 1] link that Maven provides at the end of each error message to access the relevant documentation page. You can also use the website to ask questions and get answers from other Maven users and experts.
Update your Maven version and plugins to the latest versions. Sometimes, the error you encounter may be due to a bug or a compatibility issue that has been fixed in a newer version of Maven or its plugins. You can use the mvn --update-plugins command to update your plugins automatically.
Clear your Maven cache and local repository. Sometimes, the error you encounter may be due to corrupted or outdated files in your Maven cache or local repository. You can use the mvn dependency:purge-local-repository command to delete all the files from your local repository and re-download them from the remote repositories.
Use the debug mode or the verbose mode to get more details about the error and the build process. You can use the -X option to enable debug mode or the -e option to enable verbose mode with any Maven command. These modes will print additional information that may help you identify and fix the error.
Conclusion
In this article, we have learned what Maven is, how to download and install it, how to use some common Maven commands, and how to troubleshoot some common Maven errors. We have seen that Maven is a powerful tool that can simplify and standardize the development process of Java applications. We have also seen that Maven provides a lot of features and options that can help us customize and optimize our build process according to our needs and preferences.
We hope that this article has given you a good introduction to Maven and has helped you get started with using it for your own projects. If you have any questions or feedback, please feel free to leave a comment below or contact us through our website.
FAQs
Here are some frequently asked questions about Maven with answers:
What is a POM file?A POM file is an XML file that contains information about your project and its configuration. It defines the project structure, dependencies, plugins, goals, properties, profiles, etc. A POM file is required for every Maven project and must be named pom.xml.
What is a repository?A repository is a place where Maven stores and retrieves artifacts such as JAR files, WAR files, etc. There are two types of repositories: local and remote. A local repository is a directory on your system where Maven caches all the artifacts that it downloads from remote repositories or installs from your projects. A remote repository is a server that hosts artifacts that can be accessed by other users or projects over the network.
What is a dependency?A dependency is an artifact that your project needs to run or compile. For example, if your project uses a library such as Apache Commons Lang, you need to declare it as a dependency in your POM file. Maven will then download it from a remote repository (if it is not already in your local repository) and add it to your project classpath.
What is a plugin?A plugin is an extension that adds functionality to Maven. Plugins are responsible for executing various tasks during the build process such as compiling, testing, packaging, deploying, etc. Plugins are also artifacts that can be declared as dependencies in your POM file. Maven provides a number of core plugins that cover most of the common build tasks, but you can also use third-party plugins or create your own plugins.
What is a goal?A goal is a specific task that a plugin can perform. For example, the maven-compiler-plugin has two goals: compile and testCompile. A goal can be executed by using the mvn command followed by the plugin name and the goal name. For example, mvn compiler :compile will execute the compile goal of the maven-compiler-plugin.
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