Consumer API basics in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Kafka consumer.

Kafka

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

Drag options to blanks, or click blank then click option'

A"org.apache.kafka.common.serialization.LongDeserializer"

B"org.apache.kafka.common.serialization.StringDeserializer"

C"org.apache.kafka.common.serialization.IntegerDeserializer"

D"org.apache.kafka.common.serialization.ByteArrayDeserializer"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a deserializer that does not match the message value type.

Forgetting to specify the value deserializer.

The value deserializer must match the type of the message value. Here, StringDeserializer is used to deserialize string values.

2fill in blank

medium

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

Kafka

consumer.[1](Collections.singletonList("my-topic"));

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AcommitSync

Bassign

Cpoll

Dsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Using assign instead of subscribe for topic subscription.

Calling poll before subscribing.

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];

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Apoll(100)

Bpoll()

Cpoll(Duration.ofMillis(100))

Dpoll(Duration.ofSeconds(1))

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an integer directly to poll instead of a Duration.

Using poll() without arguments which is deprecated.

Since Kafka 2.0, the poll method requires a Duration argument specifying the timeout.

4fill in blank

hard

Fill both blanks to process each record's key and value inside the poll loop.

Kafka

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

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Akey

Bvalue

Coffset

Dpartition

Attempts:

3 left

💡 Hint

Common Mistakes

Using offset or partition instead of key or value to print message content.

Mixing up key and value fields.

The key and value fields of ConsumerRecord hold the message key and value respectively.

5fill in blank

hard

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

Kafka

try {
    consumer.[1]();
} catch (Exception e) {
    System.out.println("Commit failed: ");
    e.[2]();
} finally {
    consumer.[3]();
}

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AcommitSync

BgetMessage

Cclose

DprintStackTrace

Attempts:

3 left

💡 Hint

Common Mistakes

Using commitAsync() instead of commitSync() here.

Calling getMessage() on exception instead of printStackTrace().

Forgetting to close the consumer.

commitSync() commits offsets synchronously. printStackTrace() prints error details. close() closes the consumer cleanly.