Maven configuration example for Scala

When you start to learn Scala, you might like to use tools that you are familiar to. I.e. you would like to use well known Maven to build your project and manage dependencies. In this post I’ll show you how to configure Maven to build Scala project. Fortunetly it’s very simple.

To allow the compilation of Scala source code in Maven we will will require maven plugin called maven-scala-plugin (plugin home page). This will take three steps:

First step.
To use it we’ll have to define additional Maven Repositories in you project’s <project> tag:

<repositories>
    <repository>
        <id>scala-tools.org</id>
        <name>Scala-tools Maven2 Repository</name>
        <url>https://oss.sonatype.org/content/groups/scala-tools/</url>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>scala-tools.org</id>
        <name>Scala-tools Maven2 Repository</name>
        <url>https://oss.sonatype.org/content/groups/scala-tools/</url>
    </pluginRepository>
</pluginRepositories>

Alternatively you can configure then in your settings.xml file for your Maven distribution but that would make your project environment dependent.

Second step.
Define a plugin for your project by adding the following section inside <project> -> <build> -> <plugins> tag:

<plugin>
    <groupId>org.scala-tools</groupId>
    <artifactId>maven-scala-plugin</artifactId>
    <version>${scala.maven.version}</version>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>testCompile</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Third step.
The last requirement is to define a dependency for your project containing Scala Library. To do that add this section into <project> -> <dependencies>:

<dependency>
    <groupid>org.scala-lang</groupid>
    <artifactid>scala-library</artifactid>
    <version>_here_define_scala_version_you_want_to_use_</version>
</dependency>

Result.
This all should result in a pom.xml that looks like this example:

<?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>pl.marpiec.scala</groupId>
    <artifactId>maven-example</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <scala.lang.version>2.9.1</scala.lang.version>
        <scala.maven.version>2.9.1</scala.maven.version>
    </properties>

    <repositories>
        <repository>
            <id>scala-tools.org</id>
            <name>Scala-tools Maven2 Repository</name>
            <url>https://oss.sonatype.org/content/groups/scala-tools/</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>scala-tools.org</id>
            <name>Scala-tools Maven2 Repository</name>
            <url>https://oss.sonatype.org/content/groups/scala-tools/</url>
        </pluginRepository>
    </pluginRepositories>


    <dependencies>
        <!-- Scala -->
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>${scala.lang.version}</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.scala-tools</groupId>
                <artifactId>maven-scala-plugin</artifactId>
                <version>${scala.maven.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Project structure.
When you have prepared pom.xml you can start creating your scala code. You should put it in src -> main -> scala directory (or src -> test -> scala for test code). This is the example from Intellij IDEA IDE:


Building.
And you can easily build your project just by executing mvn package command, example:

Running.
That will create jar package that you can run by that command:


That's all, I hope that you will have a great experience using Maven and Scala for your project.