producer.send(new ProducerRecord(topic, 
partition, key1, value1) , callback);

public void flush()

public Map metrics()

public void send(KeyedMessaget message) 
- sends the data to a single topic,par-titioned by key using either sync or async producer.
public void send(List>messages)
- sends data to multiple topics.
Properties prop = new Properties();
prop.put(producer.type,”async”)
ProducerConfig config = new ProducerConfig(prop);

public ProducerRecord (string topic, int partition, k key, v value)

public ProducerRecord (string topic, k key, v value)

public ProducerRecord (string topic, v value)

//import util.properties packages
import java.util.Properties;

//import simple producer packages
import org.apache.kafka.clients.producer.Producer;

//import KafkaProducer packages
import org.apache.kafka.clients.producer.KafkaProducer;

//import ProducerRecord packages
import org.apache.kafka.clients.producer.ProducerRecord;

//Create java class named “SimpleProducer”
public class SimpleProducer {
   
   public static void main(String[] args) throws Exception{
      
      // Check arguments length value
      if(args.length == 0){
         System.out.println("Enter topic name”);
         return;
      }
      
      //Assign topicName to string variable
      String topicName = args[0].toString();
      
      // create instance for properties to access producer configs   
      Properties props = new Properties();
      
      //Assign localhost id
      props.put("bootstrap.servers", “localhost:9092");
      
      //Set acknowledgements for producer requests.      
      props.put("acks", “all");
      
      //If the request fails, the producer can automatically retry,
      props.put("retries", 0);
      
      //Specify buffer size in config
      props.put("batch.size", 16384);
      
      //Reduce the no of requests less than 0   
      props.put("linger.ms", 1);
      
      //The buffer.memory controls the total amount of memory available to the producer for buffering.   
      props.put("buffer.memory", 33554432);
      
      props.put("key.serializer", 
         "org.apache.kafka.common.serializa-tion.StringSerializer");
         
      props.put("value.serializer", 
         "org.apache.kafka.common.serializa-tion.StringSerializer");
      
      Producer producer = new KafkaProducer
         (props);
            
      for(int i = 0; i < 10; i++)
         producer.send(new ProducerRecord(topicName, 
            Integer.toString(i), Integer.toString(i)));
               System.out.println(“Message sent successfully”);
               producer.close();
   }
}

javac -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*” *.java

java -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*”:. SimpleProducer 

Message sent successfully
To check the above output open new terminal and type Consumer CLI command to receive messages.
>> bin/kafka-console-consumer.sh --zookeeper localhost:2181 —topic  —from-beginning
1
2
3
4
5
6
7
8
9
10

public KafkaConsumer(java.util.Map configs)

public ConsumerRecord(string topic,int partition, long offset,K key, V value)

public ConsumerRecords(java.util.MapK,V>>> records)

import java.util.Properties;
import java.util.Arrays;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.ConsumerRecord;

public class SimpleConsumer {
   public static void main(String[] args) throws Exception {
      if(args.length == 0){
         System.out.println("Enter topic name");
         return;
      }
      //Kafka consumer configuration settings
      String topicName = args[0].toString();
      Properties props = new Properties();
      
      props.put("bootstrap.servers", "localhost:9092");
      props.put("group.id", "test");
      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.serializa-tion.StringDeserializer");
      props.put("value.deserializer", 
         "org.apache.kafka.common.serializa-tion.StringDeserializer");
      KafkaConsumer consumer = new KafkaConsumer
         (props);
      
      //Kafka Consumer subscribes list of topics here.
      consumer.subscribe(Arrays.asList(topicName))
      
      //print the topic name
      System.out.println("Subscribed to topic " + topicName);
      int i = 0;
      
      while (true) {
         ConsumerRecords records = con-sumer.poll(100);
         for (ConsumerRecord record : records)
         
         // print the offset,key and value for the consumer records.
         System.out.printf("offset = %d, key = %s, value = %s\n", 
            record.offset(), record.key(), record.value());
      }
   }
}

javac -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*” *.java

java -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*”:. SimpleConsumer 

Subscribed to topic Hello-Kafka
offset = 3, key = null, value = Hello Consumer