exec-maven-plugin could not find or load main class but output runs fine on the command line

Question

I try to use the exec-maven-plugin to run a Java program.

I use the following pom snippet:

<plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
             <configuration>
                    <executable>java</executable>
                        <arguments>
                         <argument>-Dmyproperty=myvalue</argument>
                            <argument>-cp</argument>
                            <argument>"/home/vogella/libs/*"</argument>
                            <argument>com.vogella.test.Main</argument>
                        </arguments>
    </configuration>


</plugin>

The class com.vogella.test.Main is contained in one of the jar files which are located in /home/vogella/libs/*. If I run the mvn -X clean install exec:exec command, I see the following error message:

[DEBUG] Executing command line: java -Dmyproperty=myvalue -cp "/home/vogella/libs/*" com.vogella.test.Main Error: Could not find or load main class com.vogella.test.Main

If I copy the command line (java -Dmyproperty=myvalue -cp "/home/vogella/libs/*" com.vogella.test.Main) in the shell from which I started the Maven build, then the Java program is executed correctly.

Any idea what is wrong with my Maven setup?

Answer 1

With CLI, the /home/vogella/libs/* expression is expanded by bash and resolves to the list of files. With Maven, the expression is directly executed and not expanded. so it remains "/home/vogella/libs/*" which is not a valid jar file. You'll probably have more success by using the antrun plugin and use the java Ant task in the script. Ant understands wildcards better than anything else.

Answer 2

I am not sure if this would work, but maybe you could try again using:

<commandlineArgs> 

instead. I came across this JIRA issue related to it and it sounds like what you need.

Answer 3

You need to set the classpath through dependencies. With the commandline argument -cp you set the classpath explicitly but this does not work for the maven cp. This is constructed through dependencies.

<plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.2.1</version>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>java</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <includeProjectDependencies>false</includeProjectDependencies>
                <includePluginDependencies>true</includePluginDependencies>
                <mainClass>org.eclipse.emf.mwe2.launch.runtime.Mwe2Launcher</mainClass>
                <arguments>
                    <argument>${project.basedir}/src/my/mavenized/GenerateHeroLanguage.mwe2</argument>
                </arguments>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>org.eclipse.xtext</groupId>
                    <artifactId>org.eclipse.xtext.xtext</artifactId>
                    <version>2.5.0-SNAPSHOT</version>
                </dependency>
                <dependency>
                    <groupId>org.eclipse.xtext</groupId>
                    <artifactId>org.eclipse.xtext.xbase</artifactId>
                    <version>2.5.0-SNAPSHOT</version>
                </dependency>
            </dependencies>
        </plugin>

Answer 4

As mentioned in previous answers, Maven doesn't handle well the wild cards. You should either follow the "maven way" and pass them one by one or you can try using the "commandlineArgs" instead.