How to fix NoClassDefFoundError with custom Kafka producer under Eclipse?

Question

I am trying to include Kafka module in my project.

I have added the following jars as external jar libraries in eclipse and have also update the build.xml to include the references to the jar:

• kafka-clients-0.8.2.0.jar
• kafka_2.10-0.8.2.0.jar
• scala-library-2.10.4.jar

I wrote a sample Producer class

public class KafkaWriteRequestProducer extends Thread
{
private final String topic;
private final KafkaProducer<Integer, byte[]> producer;
private final WriteRequest writeRequest;

public KafkaWriteRequestProducer(String topic, WriteRequest writeRequest)
{
    this.topic = topic;
    this.writeRequest = writeRequest;

    //Initialize the config for Kafka Producer
    Properties props = new Properties();
    props.put("bootstrap.servers", "localhost:9092");
    props.put("client.id",  "KafkaProducer");
    props.put("key.serialzer",  "org.apache.kafka.common.serialization.IntegerSerializer");
    props.put("value.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer");

    producer = new KafkaProducer<Integer, byte[]>(props);       
}
}

I have ensured that Zookeeper and Kafka brokers are running before I started this project. However, I am seeing NoClassDefFoundError() when it is trying to instantiate the new KafkaProducer().

Am I missing something obvious?

Answer 1

For completion sake, the reason why I was seeing the error was because I didn't have the jars specified in the classpath. Once, I added the jars to the classpath, it worked perfectly well.