带有Eclipse Project作为依赖项的Maven包导致NoClassDefFoundError

Question

Here is the situation. I am developing a GUI Client for (historically) CLI based processes. These processes are each under a Maven Project in Eclipse. My GUI is a separate Eclipse Maven Project. The GUI Project references the other projects in its pom.xml , the mvn package doesn't fail, yet when I run the project's ...-jar-with-dependencies.jar I get a NoClassDefFoundError for a child's project class.

Here is my pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <artifactId>proto-xml-validator</artifactId>
  <organization>
    <name>SGcib</name>
    <url>https://cib.societegenerale.com/en/</url>
  </organization>
  <build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>com.sgcib.bacardi.tools.gui.ProtoXMLValidatorGui</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
       <executions>
    <execution>
      <id>make-assembly</id> <!-- this is used for inheritance merges -->
      <phase>package</phase> <!-- bind to the packaging phase -->
      <goals>
        <goal>single</goal>
      </goals>
    </execution>
  </executions>
    </plugin>
  </plugins>
</build>
  <dependencies>
  <!-- https://mvnrepository.com/artifact/com.miglayout/miglayout-swing -->
<dependency>
    <groupId>com.miglayout</groupId>
    <artifactId>miglayout-swing</artifactId>
    <version>5.0</version>
</dependency>

  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.11.1</version>
  </dependency>
  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.11.1</version>
  </dependency>
  <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
  <dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.8</version>
  </dependency>
  <dependency>
      <groupId>org.codehaus.plexus</groupId>
      <artifactId>plexus-utils</artifactId>
      <version>1.1</version>
    </dependency>
    <dependency>
      <groupId>idea</groupId>
      <artifactId>ideaToolsUtils</artifactId>
      <version>1.2-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>bacardi</groupId>
        <version>0.0.1-SNAPSHOT</version>
        <artifactId>pnl-loader</artifactId>
    </dependency>
</dependencies>
  <groupId>bacardi</groupId>
  <version>0.0.1-SNAPSHOT</version>
</project>

And here is the stack trace

$ java -jar target/proto-xml-validator-0.0.1-SNAPSHOT-jar-with-dependencies.jar
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: idea/file/loader/runner/ValuationBVLoaderRunner
        at com.sgcib.bacardi.tools.gui.ProtoXMLValidatorGui.initialize(ProtoXMLValidatorGui.java:55)
        at com.sgcib.bacardi.tools.gui.ProtoXMLValidatorGui.<init>(ProtoXMLValidatorGui.java:33)
        at com.sgcib.bacardi.tools.gui.ProtoXMLValidatorGui$1.run(ProtoXMLValidatorGui.java:127)
        at java.awt.event.InvocationEvent.dispatch(Unknown Source)
        at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
        at java.awt.EventQueue.access$500(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: idea.file.loader.runner.ValuationBVLoaderRunner
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)

The class that triggers the NoClassDefFoundError is located under the pnl-loader artifactId in the bacardi groupId.

I have already set the scope to compile for the Project dependencies.

Does anyone know what I might be doing wrong ?

Thanks in advance.

Answer 1

Solution to my problem:

The thing was that, although my Eclipse Maven Project had the correct dependency references, it couldn't properly package them in the JAR. Indeed, a project dependency is of no use to Maven (which doesn't know what an Eclipse project is, ofc). Maven goes looking for compiled JARs in his repositories. That's what @aka-one pointed out in the comments. I had to mvn clean install the several projects that were necessary to build in order to finally package my project.