Class not found Exception for AWS lambda

Question

I created a aws Lambda function which prints hello world to console

configured lambda with package name where the class is present and method name to call and uploaded jar file to aws lambda function.

when i execute lambda i get an exception saying class not found.

with message as

{
  "errorMessage": "Class not found: com.coreservice.lambda.Handler",
  "errorType": "class java.lang.ClassNotFoundException"
}

Can't able to understand why aws unable to find class inside jar.

Below Details are project configuration

public class Handler implements RequestHandler<SNSEvent, Object> {
    
       @Override
        public Object handleRequest(final SNSEvent input, final Context context) {
                if (Objects.nonNull(input) && !CollectionUtils.isNullOrEmpty(input.getRecords())) {
                    context.getLogger().log("Hello World");
                    context.getLogger().log("queue = "+ SQS_URL);
                }
                return StringUtils.EMPTY;
            }
}

project pom :

<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.coreservice</groupId>
    <artifactId>SNS-SQS-Filter-Lambda</artifactId>
    <packaging>jar</packaging>
    <version>136.0.0-SNAPSHOT</version>
    <name>SNS-SQS-Filter-Lambda</name>
    <dependencies>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.1.0</version>
        </dependency>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-events</artifactId>
            <version>1.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.14</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.8.3</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source> <!-- or 1.8 -->
                    <target>1.8</target> <!-- or 1.8 -->
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <createDependencyReducedPom>false</createDependencyReducedPom>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

Change you lambda configuration for Handler from:

com.coreservice.lambda.Handler.handleRequest

to

com.coreservice.lambda.Handler

The com.coreservice.lambda.Handler class must implement the com.amazonaws.services.lambda.runtime.RequestHandler interface.