Can a single Spring's KafkaConsumer listener listens to multiple topic?

Question

Anyone know if a single listener can listens to multiple topic like below? I know just "topic1" works, what if I want to add additional topics? Can you please show example for both below? Thanks for the help!

@KafkaListener(topics = "topic1,topic2")
public void listen(ConsumerRecord<?, ?> record, Acknowledgment ack) {
    System.out.println(record);
} 

or

ContainerProperties containerProps = new ContainerProperties(new TopicPartitionInitialOffset("topic1, topic2", 0));

Answer 1

Yes, just follow the @KafkaListener JavaDocs:

/**
 * The topics for this listener.
 * The entries can be 'topic name', 'property-placeholder keys' or 'expressions'.
 * Expression must be resolved to the topic name.
 * Mutually exclusive with {@link #topicPattern()} and {@link #topicPartitions()}.
 * @return the topic names or expressions (SpEL) to listen to.
 */
String[] topics() default {};

/**
 * The topic pattern for this listener.
 * The entries can be 'topic name', 'property-placeholder keys' or 'expressions'.
 * Expression must be resolved to the topic pattern.
 * Mutually exclusive with {@link #topics()} and {@link #topicPartitions()}.
 * @return the topic pattern or expression (SpEL).
 */
String topicPattern() default "";

/**
 * The topicPartitions for this listener.
 * Mutually exclusive with {@link #topicPattern()} and {@link #topics()}.
 * @return the topic names or expressions (SpEL) to listen to.
 */
TopicPartition[] topicPartitions() default {};

So, your use-case should be like:

@KafkaListener(topics = {"topic1" , "topic2"})