How to Include the System Classpath in the Maven Exec Plugin?

How can I include the system classpath when using the Maven Exec Plugin?

The Maven Exec Plugin is a powerful tool for executing Java programs within a Maven project. By default, it may not include the system classpath, which can lead to issues if your application relies on classes or resources outside of the project's dependencies. This guide will walk you through the necessary steps to include the system classpath in your Maven Exec Plugin configuration.

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <version>3.0.0</version>
    <configuration>
        <mainClass>com.example.MainClass</mainClass>
        <classpathScope>system</classpathScope>
        <systemPath>${project.basedir}/lib/some-library.jar</systemPath>
    </configuration>
</plugin>

Causes

• The default configuration of the Maven Exec Plugin does not automatically include the system classpath, which can result in class not found exceptions.
• Certain libraries or dependencies may be located in the global classpath that isn’t referenced in the local Maven repository.

Solutions

• Add the configuration to include the system classpath in your `pom.xml`.
• Utilize the `exec:java` goal with the appropriate configuration to explicitly set the classpath.

Mistake: Forgetting to specify the `systemPath` which points to the actual system library or external JAR file.

Solution: Always ensure that the `systemPath` element is correctly set to the absolute path of the desired library.

Mistake: Using an incorrect version of the Maven Exec Plugin.

Solution: Check for the latest version of the Maven Exec Plugin in the official Maven repository and update your `pom.xml` accordingly.