ExceptionInInitializerError when exporting OptaPlanner as jar

Question

I have exported my OptaPlanner project to a jar. When running my jar I get the following error:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.kie.api.internal.utils.ServiceRegistry.getInstance(ServiceRegistry.java:27)
    at org.kie.api.KieServices$Factory$LazyHolder.<clinit>(KieServices.java:341)
    at org.kie.api.KieServices$Factory.get(KieServices.java:348)
    at org.optaplanner.core.config.score.director.ScoreDirectorFactoryConfig.buildDroolsScoreDirectorFactory(ScoreDirectorFactoryConfig.java:639)
    at org.optaplanner.core.config.score.director.ScoreDirectorFactoryConfig.buildScoreDirectorFactory(ScoreDirectorFactoryConfig.java:463)
    at org.optaplanner.core.config.solver.SolverConfig.buildScoreDirectorFactory(SolverConfig.java:606)
    at org.optaplanner.core.config.solver.SolverConfig.buildSolver(SolverConfig.java:514)
    at org.optaplanner.core.impl.solver.DefaultSolverFactory.buildSolver(DefaultSolverFactory.java:49)
    at org.optaplanner.examples.common.app.CommonApp.createSolutionBusiness(CommonApp.java:124)
    at org.optaplanner.examples.common.app.CommonApp.init(CommonApp.java:114)
    at org.optaplanner.examples.common.app.CommonApp.init(CommonApp.java:110)
    at org.optaplanner.examples.projectjobscheduling.app.ProjectJobSchedulingApp.main(ProjectJobSchedulingApp.java:36)
Caused by: java.lang.RuntimeException: Child services [org.kie.api.internal.assembler.KieAssemblers] have no parent
    at org.kie.api.internal.utils.ServiceDiscoveryImpl.buildMap(ServiceDiscoveryImpl.java:197)
    at org.kie.api.internal.utils.ServiceDiscoveryImpl.getServices(ServiceDiscoveryImpl.java:95)
    at org.kie.api.internal.utils.ServiceRegistryImpl.<init>(ServiceRegistryImpl.java:36)
    at org.kie.api.internal.utils.ServiceRegistryImpl$LazyHolder.<clinit>(ServiceRegistryImpl.java:32)
    ... 12 more

I saw that others had the same issue and the advise to them was to add the following code to their pom.xml file:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.2.0</version>
    <executions>
      <execution>
        <phase>package</phase>
        <goals>
          <goal>shade</goal>
        </goals>
        <configuration>
          <transformers>
            <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
            <resource>META-INF/kie.conf</resource>
            </transformer>
          </transformers>
        </configuration>
      </execution>
    </executions>
  </plugin>

For me that didn't solve my issue and I after trying all the different adjustments to my pom.xml file I could find I got a bit desperate in how to solve this.

My original pom.xml file is:

<?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.optaplanner</groupId>
    <artifactId>optaplanner</artifactId>
    <version>7.29.0.Final</version>
  </parent>

  <artifactId>optaplanner-examples</artifactId>

  <name>OptaPlanner examples</name>
  <description>
    OptaPlanner solves planning problems.
    This lightweight, embeddable planning engine implements powerful and scalable algorithms
    to optimize business resource scheduling and planning.

    This module contains the examples which demonstrate how to use it in a normal Java application.
  </description>
  <url>https://www.optaplanner.org</url>

  <properties>
    <java.module.name>org.optaplanner.examples</java.module.name>
  </properties>

  <repositories>
    <!-- Included so the examples sources in the distribution zip build out-of-the-box with maven -->
    <repository>
      <id>jboss-public-repository-group</id>
      <name>JBoss Public Repository Group</name>
      <url>https://repository.jboss.org/nexus/content/groups/public/</url>
      <layout>default</layout>
      <releases>
        <enabled>true</enabled>
        <updatePolicy>never</updatePolicy>
      </releases>
      <snapshots>
        <enabled>true</enabled>
        <updatePolicy>daily</updatePolicy>
      </snapshots>
    </repository>
  </repositories>

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-surefire-plugin</artifactId>
          <configuration>
            <forkCount>0.5C</forkCount>
            <systemPropertyVariables>
              <java.awt.headless>true</java.awt.headless>
            </systemPropertyVariables>
          </configuration>
        </plugin>
        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>exec-maven-plugin</artifactId>
          <!-- WARNING: This configuration must be run with "mvn exec:java" not "mvn exec:exec". -->
          <!-- It is impossible to write a configuration that is compatible with both exec:java and exec:exec -->
          <configuration>
            <mainClass>org.optaplanner.examples.app.OptaPlannerExamplesApp</mainClass>
            <arguments>
              <argument>-Xms256m</argument>
              <!-- Most examples run (potentially slower) with max heap of 128 MB (so -Xmx128m), but 1 example's dataset requires 1.5 GB -->
              <argument>-Xmx1536m</argument>
              <argument>-server</argument>
            </arguments>
          </configuration>
        </plugin>
        <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
          </descriptorRefs>
        </configuration>
      </plugin>
      </plugins>
    </pluginManagement>
  </build>

  <dependencies>
    <!-- Internal dependencies -->
    <dependency>
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-core</artifactId>
    </dependency>
    <dependency>
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-persistence-common</artifactId>
    </dependency>
    <dependency><!-- Most examples use the XStream integration -->
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-persistence-xstream</artifactId>
    </dependency>
    <dependency><!-- TODO add examples that use the JAXB integration -->
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-persistence-jaxb</artifactId>
    </dependency>
    <dependency><!-- TODO add examples that use the jackson integration -->
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-persistence-jackson</artifactId>
    </dependency>
    <dependency>
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-benchmark</artifactId>
    </dependency>
    <dependency>
      <groupId>org.optaplanner</groupId>
      <artifactId>optaplanner-test</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.kie</groupId>
      <artifactId>kie-api</artifactId>
    </dependency>
    <dependency>
      <groupId>org.drools</groupId>
      <artifactId>drools-decisiontables</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.drools</groupId>
      <artifactId>drools-canonical-model</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.drools</groupId>
      <artifactId>drools-model-compiler</artifactId>
      <scope>runtime</scope>
    </dependency>
    <!-- External dependencies -->
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
    </dependency>
    <dependency>
      <groupId>org.jfree</groupId>
      <artifactId>jfreechart</artifactId>
    </dependency>
    <!-- Common utils -->
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
    </dependency>
    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
    </dependency>
    <!-- Logging -->
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <scope>runtime</scope>
    </dependency>
    <!-- XML -->
    <dependency>
      <groupId>com.thoughtworks.xstream</groupId>
      <artifactId>xstream</artifactId>
    </dependency>

    <!-- Examples only dependencies. -->
    <!--
      WARNING: every examples only dependency must be properly dealt with in
      optaplanner-distribution/src/main/assembly/assembly-optaplanner.xml
    -->
    <!-- Converters -->
    <dependency>
      <groupId>org.jdom</groupId>
      <artifactId>jdom</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi-ooxml</artifactId>
      <exclusions>
        <exclusion>
          <!-- Collides with 'javax.xml.stream:stax-api' brought in by 'org.drools:drools-decisiontables'. -->
          <groupId>stax</groupId>
          <artifactId>stax-api</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>org.glassfish</groupId>
      <artifactId>javax.json</artifactId>
    </dependency>
  </dependencies>

</project>

The content of my kie.conf file is:

org.kie.api.internal.assembler.KieAssemblers = +org.optaplanner.core.impl.solver.kie.KieSolverAssemblerService

Is there anyone who knows how to solve this problem?

Answer 1

After adding the following to the <build><plugins>...</plugins></build> section of your POM, I was able to build and launch the JAR without any problems:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-shade-plugin</artifactId>
  <version>3.2.0</version>
  <executions>
    <execution>
      <phase>package</phase>
      <goals>
        <goal>shade</goal>
      </goals>
      <configuration>
        <transformers>
          <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">          
        <mainClass>org.optaplanner.examples.app.OptaPlannerExamplesApp</mainClass>
          </transformer>
          <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
            <resource>META-INF/kie.conf</resource>
          </transformer>
        </transformers>
      </configuration>
    </execution>
  </executions>
</plugin>

This change actually builds the shaded JAR (which your original version doesn't do).