[Solved] Given the following code snippet, what will be printed if the topic test-topic has two messages with values "Hello" and "World"?consumer.subscribe(Collections.singletonList("test-topic"));... | Kafka

Kafka - with Java/Python

Given the following code snippet, what will be printed if the topic test-topic has two messages with values "Hello" and "World"?

consumer.subscribe(Collections.singletonList("test-topic"));
ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(1000));
for (ConsumerRecord<String, String> record : records) {
    System.out.println(record.value());
}

ACompilation error

BWorld\nHello

CHello\nWorld

DNo output

Step-by-Step Solution

Solution:

Step 1: Understand subscription and polling
The consumer subscribes to the topic and polls for messages, which returns all available records.
Step 2: Analyze the loop output
The loop prints each record's value in the order received, which is typically the order messages were produced: "Hello" then "World".
Final Answer:
Hello\nWorld -> Option C
Quick Check:
poll() returns messages in order = D [OK]

Quick Trick: poll() returns messages in production order [OK]

Common Mistakes:

MISTAKES

Assuming reversed order of messages
Expecting no output if poll timeout is short
Confusing compile errors with runtime behavior

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More Kafka Quizzes

Given the following code snippet, what will be printed if the topic test-topic has two messages with values "Hello" and "World"?

Step 1: Understand subscription and polling

Step 2: Analyze the loop output

Final Answer:

Quick Check:

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