Exec

http://mojo.codehaus.org/exec-maven-plugin/
Also see Application Assembler.

Example

Command Line

To run MainClass in the current VM with the enclosing project’s dependencies as classpath:

mvn exec:java -Dexec.mainClass="com.company.app.MainClass"

pom.xml

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <configuration>
                <executable>java</executable>
                <!-- This adds target/test-classes to the classpath.
                <classpathScope>test</classpathScope>
                -->
                <arguments>
                    <argument>-classpath</argument>
                    <!-- automatically creates the classpath using all project dependencies,
                    also adding the project build directory -->
                    <classpath/>
                    <argument>com.sample.App</argument>
                    <argument>${project.artifactId}</argument>
                </arguments>
            </configuration>
        </plugin>
    </plugins>
</build>

Then run the application:

mvn exec:exec

Multi Module

To use the exec plugin in a multi module project, just change into the module folder before running the command.

Source Code

To checkout the source code for this project:

svn checkout http://svn.codehaus.org/mojo/trunk/mojo/exec-maven-plugin exec-maven-plugin

Issues

Class Loading Issues

Cannot find a solution for this issue when using the Exec Plugin, but I have found a Surefire (Unit Testing).

java.lang.LinkageError: loader constraints violated when linking javax/xml/namespace/QName class

NullPointerException

Trying to run the application from the wrong folder:

mvn exec:java -Dexec.mainClass="com.sample.Write"

and I get this error:

[INFO] [exec:java]
[ERROR] BUILD ERROR
constituent[0]: file:/usr/share/maven/lib/maven-core-2.0.6-uber.jar
java.lang.NullPointerException
        at org.apache.maven.usability.MojoExecutionExceptionDiagnoser.diagnose(MojoExecutionExceptionDiagnoser.java:64)

Two things will cause this error:

Write.class did not even exist in the target/classes folder.
Also had the same error trying to run a non-public class.

Offline

It is often helpful to add the offline (-o) parameter when using the exec plugin. Your application will start more quickly because Maven will only check your local repository for updated artifacts.

Parameters

Make sure you use the latest version of the plugin (-U to update):

mvn exec:java -Dexec.mainClass="com.sample.App" -Dexec.args="81"

For more information see Jira MEXEC-11.