[FIXED] Spring Boot JAR file not working with ClassNotFoundException

Issue

I have a Spring Boot Application that is working.

I did

mvn clean package

and the .jar file is my target folder.

Then I try to execute the following command:

java -jar .\target\my-application-0.0.1-SNAPSHOT.jar

and I get the following Error:

Exception in thread "main" java.lang.ClassNotFoundException: C:\Users\test\example-application\example-app/src/main/test/ExampleApplication
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Class.java:467)
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:46)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:65)

Researching on stackoverflow just recommend an issue that I already included ... It was recommended to include this plugin in order to include the maven jars into the project .... spring-boot-maven-plugin

        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>

What else could be the reason for it not working?

Solution

The class name in the exception is a file name and not a class name. That makes me suspect that you have specified the main class incorrectly. Have you specified the name of the class in the spring-boot-maven-plugin with

<configuration>
  <mainClass>foo.bar.ExampleApplication</mainClass>
</configuration>

or as a Main-Class in the manifest? Note that you should use dot notation for packages...

Answered By - Per Huss
Answer Checked By - Gilberto Lyons (JavaFixing Admin)