org.apache.kafka.streams.kstream

Interface ValueMapperWithKey<K,V,VR>

Type Parameters:

K - key type

V - value type

VR - mapped value type

public interface ValueMapperWithKey<K,V,VR>

The ValueMapperWithKey interface for mapping a value to a new value of arbitrary type. This is a stateless record-by-record operation, i.e, apply(Object, Object) is invoked individually for each record of a stream (cf. ValueTransformer for stateful value transformation). If ValueMapperWithKey is applied to a key-value pair record the record's key is preserved. Note that the key is read-only and should not be modified, as this can lead to corrupt partitioning. If a record's key and value should be modified KeyValueMapper can be used.

See Also:

KeyValueMapper, ValueTransformer, ValueTransformerWithKey, KStream.mapValues(ValueMapper), KStream.mapValues(ValueMapperWithKey), KStream.flatMapValues(ValueMapper), KStream.flatMapValues(ValueMapperWithKey), KTable.mapValues(ValueMapper), KTable.mapValues(ValueMapperWithKey)

Method Summary

Modifier and Type	Method and Description
VR	apply(K readOnlyKey, V value) Map the given [key and ]value to a new value.

Method Detail

apply

VR apply(K readOnlyKey,
         V value)

Map the given [key and ]value to a new value.

Parameters:

readOnlyKey - the read-only key

value - the value to be mapped

Returns:

the new value