running a maven scala project - scala

Question

Im starting to learn scala and mongo , my IDE is intellij IDEA. I created a scala project using
mvn:archetype-generate
and typed a simple hello world program in the IDEA with some arithmetic options such as
println(5)
val i = 1+2
println(i)
Then i compiled it using
mvn compile
It said
build success
But now how should i execute my application and verify the output. There isn't a single article which explains how to start off with scala,maven,idea and i am entirely new to all of this. any help would be useful for me.

Answer 1

maven-exec-plugin
Try with this code:
package com.example
object Main {
def main(args: Array[String]) {
println(5)
val i = 1 + 2
println(i)
}
}
Place it under /src/main/scala/com/example/Main.scala and run it using:
$ mvn package exec:java -Dexec.mainClass=com.example.Main
If you don't want to pass mainClass manually, you can do this in plugin configuration:
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.1</version>
<configuration>
<mainClass>com.example.Main</mainClass>
</configuration>
</plugin>
</plugins>
There are other possibilities, this is the easiest one. Of course in IntelliJ you should be able to run the program directly.
maven-jar-plugin
If you want to ship the application, use maven-jar-plugin to add Main-Class and Class-Path entries to the manifest:
Main-Class: com.example.Main
Class-Path: lib/scala-library-2.9.0-1.jar lib/slf4j-api-1.6.1.jar ...
The following configuration does that and also copies all the dependencies (including Scala runtime library) to target/lib.
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<archive>
<manifest>
<mainClass>com.example.Main</mainClass>
<addClasspath>true</addClasspath>
<classpathLayoutType>custom</classpathLayoutType>
<customClasspathLayout>lib/$${artifact.artifactId}-$${artifact.version}$${dashClassifier?}.$${artifact.extension}
</customClasspathLayout>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.3</version>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
Now you can simply run your application by (note the target/lib directory is required):
$ java -jar target/your_app-VERSION.jar
You can ship your application simply by copying your JAR file along with /lib subdirectory.
Also see Exec Maven Plugin and Playing with Scala and Maven.