Java consumer client in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Kafka consumer with the correct group ID.

Kafka

Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("group.id", "[1]");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");

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Amy-group

Bgroup-123

Cdefault

Dconsumer1

Attempts:

3 left

💡 Hint

Common Mistakes

Using an empty string as group ID

Using an invalid property key

The group ID identifies the consumer group. Here, 'consumer1' is used as the group ID.

2fill in blank

medium

Complete the code to subscribe the consumer to a topic named 'test-topic'.

Kafka

KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
consumer.[1](Collections.singletonList("test-topic"));

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Asubscribe

Bconnect

Clisten

Dassign

Attempts:

3 left

💡 Hint

Common Mistakes

Using assign() instead of subscribe()

Using a non-existent method like listen()

The subscribe() method is used to subscribe the consumer to one or more topics.

3fill in blank

hard

Fix the error in the code to correctly poll messages from Kafka.

Kafka

ConsumerRecords<String, String> records = consumer.[1](100);

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Apoll

Bfetch

Cread

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using fetch() or read() instead of poll()

Passing wrong argument types to poll()

The poll() method is used to fetch records from Kafka. The argument should be a Duration in newer versions, but here an integer is used for simplicity.

4fill in blank

hard

Fill both blanks to process each record and print its key and value.

Kafka

for (ConsumerRecord<String, String> record : records) {
    System.out.println("Key: " + record.[1]() + ", Value: " + record.[2]());
}

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Akey

Bvalue

CgetKey

DgetValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using key() or value() methods which do not exist

Trying to access key or value as public fields

The ConsumerRecord class provides getKey() and getValue() methods to access the key and value.

5fill in blank

hard

Fill all three blanks to commit offsets synchronously after processing records.

Kafka

try {
    consumer.[1]();
} catch ([2] e) {
    e.[3]();
}

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AcommitSync

BcommitAsync

CprintStackTrace

DInterruptedException

Attempts:

3 left

💡 Hint

Common Mistakes

Using commitAsync() instead of commitSync()

Catching wrong exception types

Not printing the stack trace in catch block

commitSync() commits offsets synchronously. InterruptedException is caught and printStackTrace() prints the error.