[Solved] What is wrong with this Kafka Streams aggregation code? var aggregated = stream.groupBy((k, v) -> v.getCategory()).aggregate( () -> 0, (key, value, aggregate) -> aggregate + value.getAmount() ); | Kafka

Kafka - Streams

What is wrong with this Kafka Streams aggregation code?

var aggregated = stream.groupBy((k, v) -> v.getCategory()).aggregate(
  () -> 0,
  (key, value, aggregate) -> aggregate + value.getAmount()
);

Aaggregate() requires a Materialized parameter

BInitial value must be a Long, not int

CgroupBy() cannot use lambda expressions

Daggregate() cannot sum values

Step-by-Step Solution

Solution:

Step 1: Check aggregate() method requirements
The aggregate() method requires a Materialized parameter to specify state store details.
Step 2: Identify missing Materialized parameter
In the code, Materialized is missing, which will cause a compilation error.
Final Answer:
aggregate() requires a Materialized parameter -> Option A
Quick Check:
aggregate() needs Materialized for state store [OK]

Quick Trick: Always provide Materialized when using aggregate() [OK]

Common Mistakes:

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