Simple Kafka Consumer not receiving messages

Question

I am a newbie to Kafka and running a simple kafka consumer/producer example as given on KafkaConsumer and KafkaProducer. When I am running consumer from terminal, consumer is re

Answer 1

First check what all the groups are available by using :

./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --list

Then check for which group your topic belongs by using below cmd :

./kafka-consumer-groups.sh --bootstrap-server localhost:9092 --group  --describe

Once you find your topic and associated group name (just replace group.id with your group if it not belongs to default group) then try with below prop and let me know if it works :

  props.put("bootstrap.servers", "localhost:9092");
  props.put("group.id", "test-consumer-group"); // default topic name
  props.put("enable.auto.commit", "true");
  props.put("auto.commit.interval.ms", "1000");
  props.put("session.timeout.ms", "30000");
  props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
  props.put("value.deserializer","org.apache.kafka.common.serialization.StringDeserializer");
  KafkaConsumer consumer = new KafkaConsumer(props);

  //Kafka Consumer subscribes list of topics here.
  consumer.subscribe(Arrays.asList(topicName));  // replace you topic name

  //print the topic name

  java.util.Map> listTopics = consumer.listTopics();
  System.out.println("list of topic size :" + listTopics.size());

  for(String topic : listTopics.keySet()){
      System.out.println("topic name :"+topic);
  }