org.apache.kafka.streams.kstream

Interface Initializer<VA>

Type Parameters:

VA - aggregate value type

@InterfaceStability.Unstable
public interface Initializer<VA>

The Initializer interface for creating an initial value in aggregations. Initializer is used in combination with Aggregator.

See Also:

Aggregator, KGroupedStream.aggregate(Initializer, Aggregator, org.apache.kafka.common.serialization.Serde, String), KGroupedStream.aggregate(Initializer, Aggregator, org.apache.kafka.streams.processor.StateStoreSupplier), KGroupedStream.aggregate(Initializer, Aggregator, Windows, org.apache.kafka.common.serialization.Serde, String), KGroupedStream.aggregate(Initializer, Aggregator, Windows, org.apache.kafka.streams.processor.StateStoreSupplier), KGroupedStream.aggregate(Initializer, Aggregator, Merger, SessionWindows, org.apache.kafka.common.serialization.Serde, String), KGroupedStream.aggregate(Initializer, Aggregator, Merger, SessionWindows, org.apache.kafka.common.serialization.Serde, org.apache.kafka.streams.processor.StateStoreSupplier)

Method Summary

Methods

Modifier and Type	Method and Description
VA	apply() Return the initial value for an aggregation.

Method Detail

apply

VA apply()

Return the initial value for an aggregation.

Returns:

the initial value for an aggregation