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How to resolve java.lang.reflect.InvocationTargetException when running springboot applications

Cowrie
Cowrie
Dev @ Bswen

Problem

In this post, I will demonstrate how to resolve the following error when running Spring Boot applications:

Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more

Environments

The environments are as follows:

  • Java version: JDK 1.8
  • Spring Boot version: 2.1.5.RELEASE

The Maven POM

The code is as follows:

pom.xml
<?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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>


    <groupId>com.bswen.test</groupId>
    <artifactId>shopper</artifactId>
    <version>1.0-SNAPSHOT</version>


    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>


    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>


    <dependencies>
        <!-- springboot web and jsp and tomcat embeded -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                        <configuration>
                            <classifier>exec</classifier>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Run the code and get error

When I run the Spring Boot app after building it like this:

java -jar shopper-1.0-SNAPSHOT-exec.jar

I get this error:

Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more
Caused by: java.lang.reflect.InvocationTargetException
        ... 1024 more

How to resolve the problem

I think this error is caused by the missing main class in the JAR. Let’s inspect the JAR by unzipping it:

The content of META-INF/MANIFEST.MF is:

➜  target git:(master) ✗ cat META-INF/MANIFEST.MF
Manifest-Version: 1.0
Implementation-Title: shopper
Implementation-Version: 1.0-SNAPSHOT
Start-Class: org.springframework.boot.loader.JarLauncher
Spring-Boot-Classes: BOOT-INF/classes/
Spring-Boot-Lib: BOOT-INF/lib/
Build-Jdk-Spec: 1.8
Spring-Boot-Version: 2.1.5.RELEASE
Created-By: Maven Archiver 3.4.0
Main-Class: org.springframework.boot.loader.JarLauncher

In fact, Spring Boot expects that there is a main-class to be set to org.springframework.boot.loader.JarLauncher in the MANIFEST.MF, and a start-class to be set to the Spring Boot application’s main class.

To fix this, add the following property to your Maven POM:

<properties>
    <!-- The main class to start by executing "java -jar" -->
    <start-class>com.bswen.test.shopper.Application</start-class>
</properties>

Alternatively, change the Maven build plugin configuration:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <mainClass>com.bswen.test.shopper.Application</mainClass>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
            <configuration>
                <classifier>exec</classifier>
            </configuration>
        </execution>
    </executions>
</plugin>

After rebuilding, the META-INF/MANIFEST.MF in the executable JAR will look like this:

➜  target git:(master) cat META-INF/MANIFEST.MF
Manifest-Version: 1.0
Implementation-Title: shopper
Implementation-Version: 1.0-SNAPSHOT
Start-Class: com.bswen.test.shopper.Application  #this is the keypoint
Spring-Boot-Classes: BOOT-INF/classes/
Spring-Boot-Lib: BOOT-INF/lib/
Build-Jdk-Spec: 1.8
Spring-Boot-Version: 2.1.5.RELEASE
Created-By: Maven Archiver 3.4.0
Main-Class: org.springframework.boot.loader.JarLauncher

You can see that, after changing the POM, you get a correct start-class in the MANIFEST.MF.

Summary

In this post, we explored how to resolve the java.lang.reflect.InvocationTargetException error in Spring Boot applications. The key issue was the incorrect configuration of the start-class parameter in the MANIFEST.MF file. By correctly setting the start-class to the main class of the Spring Boot application, either through the Maven POM properties or the Spring Boot Maven plugin configuration, the issue can be resolved. Always ensure that your MANIFEST.MF file is correctly configured to avoid such runtime errors.

Final Words + More Resources

My intention with this article was to help others who might be considering solving such a problem. So I hope that’s been the case here. If you still have any questions, don’t hesitate to ask me by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

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