I had read all the articles about AWS Lambda dealing with .jar file but unfortunately I did not find the answer. Currently I had my code using the command line down below to upload to S3 (since my .jar file is too big so I can’t directly upload from lambda console:

mvn clean package shade:shade -D maven.test.skip=true

Also I had open the access policy to S3fullAccess for my lambda function, and my handler is set to:

com.example.demo.controller.AlgoCalculationHandler::handleRequest

here is my code structure

I had been stuck for hours that I constantly got this error, I did not get more info by checking cloudwatch log:

{
  "errorMessage": "Class not found: com.example.demo.controller.AlgoCalculationHandler",
  "errorType": "java.lang.ClassNotFoundException"
}

START RequestId: f8b7a098-e038-489f-ad72-28f0ff9fe77d Version: $LATEST
Class not found: com.example.demo.controller.AlgoCalculationHandler: java.lang.ClassNotFoundException
java.lang.ClassNotFoundException: com.example.demo.controller.AlgoCalculationHandler
    at java.base/java.net.URLClassLoader.findClass(Unknown Source)
    at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
    at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Unknown Source)

END RequestId: f8b7a098-e038-489f-ad72-28f0ff9fe77d
REPORT RequestId: f8b7a098-e038-489f-ad72-28f0ff9fe77d  Duration: 3.87 ms   Billed Duration: 4 ms   Memory Size: 512 MB Max Memory Used: 90 MB  

Before I can successfully use lambda since my .jar is relatively smaller, I always upload my .jar file directly from lambda page, this is my first time to upload .jar to S3, I am not sure if this is any connection between this practice?

Thanks in advance if there’s anyone can help!

Here is my pom.xml setting

<dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>aws-lambda-java-core</artifactId>
    <version>1.1.0</version>
</dependency>


        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>${maven-shade-plugin.version}</version>
            <configuration>
                <createDependencyReducedPom>false</createDependencyReducedPom>
            </configuration>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>