Maven exec plugin ClassNotFoundException

Question

I'm using the Maven exec plugin to run a java application from the command line with the command mvn exec:java. I have specified the main class in the pom.xml and the associated dependencies.

<groupId>com.example.MyApp</groupId>
<artifactId>MyApp</artifactId>
<version>1.0.0</version>
<build>
  <plugins>
     <plugin>
       <groupId>org.codehaus.mojo</groupId>
       <artifactId>exec-maven-plugin</artifactId>
       <version>1.2.1</version>
       <executions>
         <execution>
           <goals>
             <goal>java</goal>
          </goals>
         </execution>
       </executions>
       <configuration>
          <mainClass>com.example.myclass</mainClass>
          <arguments>
            <argument>configFile</argument>
            <argument>properties</argument>
          </arguments>
       </configuration>
     </plugin>

I also specify a number of dependencies...

<dependencies>
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
    <type>jar</type>
</dependency>
<dependency>
    <groupId>com.example.MyLibrary</groupId>
    <artifactId>MyLibrary</artifactId>
    <version>1.0.0</version>
</dependency>

The MyApp program reads a config file which is passed in as a command line argument. The config file contains the name of a class which is located in MyLibrary. So the class could be com.mypackage.driver.MyClass which is located in MyLibrary which is a dependency of the MyApp jar listed above. However when I try to run this I get a ClassNotFoundException...

Update---- I'm using the system classloader to load the classes which are passed in on the command line for the MyApp program

ClassLoader loader = ClassLoader.getSystemClassLoader();

I'm thinking that this is causing the problem as it is looking for the classes on the default classpath which does not contain the dependencies.

Any hints on what I'm doing wrong here?

Caleb · Accepted Answer · 2014-03-25 21:36:18Z

18

Are you still looking for an answer to this question? I had the exact same issue, and finally figured it out.

You need to add includePluginDependencies to your configuration to make the plugin search your dependencies for the main class:

<configuration>
  <includePluginDependencies>true</includePluginDependencies>
  <mainClass>com.example.myclass</mainClass>
  <arguments>
    <argument>configFile</argument>
    <argument>properties</argument>
  </arguments>
</configuration>

See here: http://mojo.codehaus.org/exec-maven-plugin/java-mojo.html#includePluginDependencies

answered Mar 25, 2014 at 21:36

Caleb

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2 Comments

Maxi Wu Over a year ago

I have the same issue, added includePluginDependencies, still ClassNotFoundException. Any other suggestions?

andrexorg Over a year ago

Also adding includePluginDependencies the error continue to face out. The reason was "clean" goal. In my case just remove it and it works. @MaxiWu

Jens Baitinger · Accepted Answer · 2013-12-20 14:46:50Z

2

You need to add the dependency as dependency of the execution plugin, so the execution plugin can load the class you configured com.example.myclass:

<plugins>
 <plugin>
   <groupId>org.codehaus.mojo</groupId>
   <artifactId>exec-maven-plugin</artifactId>
   <version>1.2.1</version>
   [...]
   <dependencies>
     <dependency>
       <groupId>com.example.MyLibrary</groupId>
       <artifactId>MyLibrary</artifactId>
       <version>1.0.0</version>
       <type>jar</type>
     </dependency>

 </plugin>

answered Dec 20, 2013 at 14:46

Jens Baitinger

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1 Comment

Barry Over a year ago

Thanks for the response, I've added the dependency to the plugin, but it's still giving me a classnotfound error. I've followed this example here mojo.codehaus.org/exec-maven-plugin/examples/…

Moritz Petersen · Accepted Answer · 2013-12-20 16:28:09Z

1

You can let the classpath get generated like this:

    <configuration>
      <executable>java</executable>
      <arguments>
        <argument>-Dmyproperty=myvalue</argument>
        <argument>-classpath</argument>
        <!-- automatically creates the classpath using all project dependencies,
             also adding the project build directory -->
        <classpath/>
        <argument>com.example.Main</argument>
        ...
      </arguments>
    </configuration>

edited Dec 20, 2013 at 16:28

answered Dec 20, 2013 at 14:39

Moritz Petersen

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3 Comments

Barry Over a year ago

Hi @Moritz can you elaborate further on this, I was under the impression that once I ran mvn exec:java then the dependencies that were defined by this project would automatically be included on the classpath...

Sridhar Sarnobat Over a year ago

Where do you put this? Inside the <plugin>?

Moritz Petersen Over a year ago

yep, this is the config of the plugin

Girivasan · Accepted Answer · 2021-03-04 12:34:11Z

1

Try mvn clean compile exec:java

Sometimes we forget to compile the code and when you run mvn exec:java without compiling, then obviously maven cannot find the compiled class files and complain about ClassNotFoundException

answered Mar 4, 2021 at 12:34

Girivasan

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Comments

jjmartinez · Accepted Answer · 2013-12-20 14:39:25Z

0

Before to execute from command line, you should import also in command line your library. You can use this command with your expecific name and info of your library:

mvn install:install-file -Dfile=MyLibrary.jar -DgroupId=com.example.MyLibrary -DartifactId=MyLibrary -Dversion=1.0.0 -Dpackaging=jar

answered Dec 20, 2013 at 14:39

jjmartinez

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1 Comment

Barry Over a year ago

Hi Thanks for the response, the jar is located in my local repository already

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