V - value type
VR - mapped value type
public interface ValueMapper<V,VR>
ValueMapper interface for mapping a value to a new value of arbitrary type.
This is a stateless record-by-record operation, i.e,
apply(Object) is invoked individually for each record
of a stream (cf.
ValueTransformer for stateful value transformation).
ValueMapper is applied to a
key-value pair record the record's
key is preserved.
If a record's key and value should be modified
KeyValueMapper can be used.