Error java.lang.NoClassDefFound with maven

Question

Hello everyone and thank you in advance for you help. I'm a student and learning java. For this semester we have a group project were we need to complete a code with already some functions implemented. My main task was to implement an algorithm in the class assign from the directory assignment mainly using functions from class in the directory data model. Every class though in different directorie is in the same package. When calling static fields from data model classes in assign I encounter no problem. However when calling a method here is what I get error ClassDefNotFound. I shall add that I run the program with a .jar file. I tried a LOT of things to solve the problem but unfortunately I haven't solved it yet and I'm starting to run out for time so here I am looking for your help.

I tried to change the pom.xml file from assignment directory by adding in the configuration however it's still not working. Besides I'm confused by which path should I exactly write down. I know it as to be an absolute path but I can't writ my user directory because the project is supposed to work on any computer.

Thanks again for you future help. I've been pulling my hairs out on this one thing for ever so any help solving this would be a life saver !

Answer 1

Think you are missing the dependencies when generating the jar. thats why it says that the class isn't defined, try this in your pom.xml

source: Including dependencies in a jar with Maven

<build>
    <plugins>
      <!-- any other plugins -->
      <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>
  </build>

Personal pom.xml example (notice at the begining the use of the above plugin and also I defined a manifest, try both ways:

<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>
    <groupId>NuevaUtilidadExcel</groupId>
    <artifactId>NuevaUtilidadExcel</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.0.0</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <mainClass>com.nuevaUtilidad.vista.InterfazPrincipal</mainClass>
                        </manifest>
                    </archive>
                </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>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>unknown-jars-temp-repo</id>
            <name>A temporary repository created by NetBeans for libraries and jars it could not identify. Please replace the dependencies in this repository with correct ones and delete this repository.</name>
            <url>file:${project.basedir}/lib</url>
        </repository>
        <repository>
            <id>netbeans</id>
            <name>Netbeans rep</name>
            <url>http://bits.netbeans.org/maven2/</url>
        </repository>

    </repositories>
    <dependencies>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>4.1.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>4.1.0</version>
        </dependency>

        <dependency>
            <groupId>com.opencsv</groupId>
            <artifactId>opencsv</artifactId>
            <version>4.0</version>
        </dependency>


        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>2.9.6</version>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.9</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

        <dependency>
            <groupId>org.apache.xmlbeans</groupId>
            <artifactId>xmlbeans</artifactId>
            <version>3.0.1</version>
        </dependency>

        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc6</artifactId>
            <version>11.2.0</version>
        </dependency>

        <dependency>
            <groupId>com.toedter</groupId>
            <artifactId>jcalendar</artifactId>
            <version>1.4</version>
        </dependency>

    </dependencies>
    <name>NuevaUtilidadExcelSVG</name>
</project>