Setting Up a Kafka Consumer in Java

What is a Kafka Consumer?

A Kafka Consumer is a component of Apache Kafka, a distributed streaming platform, which is used to read and process messages from Kafka topics. It subscribes to one or more Kafka topics and processes the stream of records sent by producers.

Kafka Consumers are essential for systems that require real-time data processing. They provide scalable and fault-tolerant methods to read from and process streams of data.

Use Cases:

  • Real-Time Analytics: Processing data streams for real-time analytics applications, such as dashboard updates or real-time monitoring.
  • Log Aggregation: Consuming and processing logs from various services for centralized monitoring or analysis.
  • Stream Processing: As part of a larger stream processing architecture, for tasks like aggregating data streams or triggering actions based on stream patterns.

Setting Up a Kafka Consumer in Java


  • Java (JDK 1.8 or higher)
  • Apache Kafka (Installation guide: Apache Kafka Quickstart)
  • Maven or Gradle (for dependency management)

Step-by-Step Guide

Step 1: Add Kafka Client Dependency

Include the Kafka clients dependency in your pom.xml (Maven) or build.gradle (Gradle).


Copy code


implementation 'org.apache.kafka:kafka-clients:{kafka-version}'

Replace {kafka-version} with the version of Kafka you're using.

Step 2: Configure Kafka Consumer

Define the configuration properties for the Kafka consumer:

import java.util.Properties;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;

Properties properties = new Properties();
properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
properties.put(ConsumerConfig.GROUP_ID_CONFIG, "my-consumer-group");
properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");

Step 3: Create the Kafka Consumer

Instantiate the Kafka consumer with the defined configuration:

import org.apache.kafka.clients.consumer.KafkaConsumer;

KafkaConsumer<String, String> consumer = new KafkaConsumer<>(properties);

Step 4: Subscribe to Topics

Subscribe the consumer to one or more topics:


Step 5: Poll for Data

Continuously poll for new data from the subscribed topics:

while (true) {
    ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
    for (ConsumerRecord<String, String> record : records) {
        System.out.printf("Received message: key = %s, value = %s%n", record.key(), record.value());

Step 6: Close the Consumer

Ensure to close the consumer gracefully:



Setting up a Kafka Consumer in Java enables your application to process streaming data in real time. This setup is key for building scalable and robust data processing applications.

For advanced consumer configurations and usage, including committing offsets and handling rebalance, refer to the [official Kafka documentation[(]. This guide offers the foundational steps to integrate Kafka Consumers into your Java applications.