[Solved] What will be the output of this Kafka Streams code snippet?StreamsBuilder builder = new... // Assume input-topic has messages: {"1":"ok"}, {"2":"error found"} // What messages appear in error-topic? | Kafka

Kafka - Advanced Stream Processing

What will be the output of this Kafka Streams code snippet?

StreamsBuilder builder = new StreamsBuilder();
KStream stream = builder.stream("input-topic");
KStream filtered = stream.filter((k, v) -> v.contains("error"));
filtered.to("error-topic");
// Assume input-topic has messages: {"1":"ok"}, {"2":"error found"}
// What messages appear in error-topic?

A{"1":"ok"}

B{"2":"error found"}

C{"1":"ok"}, {"2":"error found"}

D{} (empty)

Step-by-Step Solution

Solution:

Step 1: Understand the filter condition
The filter keeps messages where value contains "error".
Step 2: Check input messages against filter
Message {"2":"error found"} contains "error", so it passes; {"1":"ok"} does not.
Final Answer:
{"2":"error found"} -> Option B
Quick Check:
Filter output = messages containing "error" [OK]

Quick Trick: Filter keeps only matching messages in output topic [OK]

Common Mistakes:

Assuming all messages pass filter
Confusing key and value in filter
Ignoring filter condition logic

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More Kafka Quizzes

What will be the output of this Kafka Streams code snippet?

Step 1: Understand the filter condition

Step 2: Check input messages against filter

Final Answer:

Quick Check:

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