java.lang.NoClassDefFoundError: org/apache/poi/ss/

I've made a small application that reads from an excel (xls file) and displays the contents to a JTable. Everything is working fine in eclipse, yet when I create the jar file and try to run it, I get the following issue:

java.lang.NoClassDefFoundError: org/apache/poi/ss/usermodel/Row

The weird thing I find is that the issue is with the Row, when Workbook and Sheet is called before the row and gives no trouble (at least from what I can see).

I've researched alot and it mainly seems to be with the jar files not being in the Class-Path, but opening the jar and the manifest file I can see all the jars are present.

Class-Path: poi-ooxml-4.0.1.jar poi-4.0.1.jar commons-codec-1.11.jar commons-collections4-4.2.jar commons-math3-3.6.1.jar commons-compress-1.18.jar curvesapi-1.05.jar poi-ooxml-schemas-4.0.1.jar xmlbeans-3.0.2.jar

This is what I have in my pom.xml file:

<build>
 <plugins>
  <plugin>
    <!-- Build an executable JAR -->
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <configuration>
      <archive>
       <manifest>
          <addClasspath>true</addClasspath>
          <classpathPrefix>./</classpathPrefix>
           <mainClass>com.clientdb.classes.DynamicRegForm</mainClass>
         </manifest>
       </archive>
     </configuration>
    </plugin>
  </plugins>
</build>
<dependencies>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.0.1</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.0.1</version>
   </dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml-schemas</artifactId>
<version>4.0.1</version>
</dependency>
</dependencies>

I have also tried downloading the jar files and adding them to the project instead of adding the dependency to pom file, and still the same error. Any ideas?

Probably you are getting this only when you are running your jar because the dependencies are not available/packaged inside of it.

Try generating a "fat jar" (also known as uber-jar), it will package all your dependencies inside the jar:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <finalName>YOUR_JAR_FINAL_NAME</finalName>
            </configuration>
        </plugin>
    </plugins>
</build>

Documentation related to the maven-shade-plugin can be found in here

UPDATE: Since you are using a runnable jar file, you can follow this section of the documentation related to Executable Jars