Quick Start Guide

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <version>4.1.1</version>
</dependency>

implementation 'org.apache.kafka:kafka-clients:4.1.1'

import org.apache.kafka.clients.producer.*;
import java.util.Properties;

Properties props = new Properties();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,
    "org.apache.kafka.common.serialization.StringSerializer");
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,
    "org.apache.kafka.common.serialization.StringSerializer");

Producer<String, String> producer = new KafkaProducer<>(props);

ProducerRecord<String, String> record =
    new ProducerRecord<>("my-topic", "key", "value");

producer.send(record, (metadata, exception) -> {
    if (exception != null) {
        exception.printStackTrace();
    } else {
        System.out.println("Sent to partition " + metadata.partition() +
            " at offset " + metadata.offset());
    }
});

producer.close();

import org.apache.kafka.clients.consumer.*;
import java.time.Duration;
import java.util.Collections;
import java.util.Properties;

Properties props = new Properties();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(ConsumerConfig.GROUP_ID_CONFIG, "my-group");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
    "org.apache.kafka.common.serialization.StringDeserializer");
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
    "org.apache.kafka.common.serialization.StringDeserializer");

Consumer<String, String> consumer = new KafkaConsumer<>(props);
consumer.subscribe(Collections.singletonList("my-topic"));

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

import org.apache.kafka.streams.*;
import org.apache.kafka.streams.kstream.*;
import java.util.Properties;

Properties props = new Properties();
props.put(StreamsConfig.APPLICATION_ID_CONFIG, "my-streams-app");
props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");

StreamsBuilder builder = new StreamsBuilder();
KStream<String, String> source = builder.stream("input-topic");
source.mapValues(value -> value.toUpperCase())
      .to("output-topic");

KafkaStreams streams = new KafkaStreams(builder.build(), props);
streams.start();

Runtime.getRuntime().addShutdownHook(new Thread(streams::close));

import org.apache.kafka.clients.admin.*;
import java.util.*;

Properties props = new Properties();
props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");

try (Admin admin = Admin.create(props)) {
    // Create topic
    NewTopic newTopic = new NewTopic("my-topic", 3, (short) 2);
    admin.createTopics(Collections.singletonList(newTopic)).all().get();
    
    // List topics
    Set<String> topics = admin.listTopics().names().get();
    System.out.println("Topics: " + topics);
}