com.hazelcast.mapreduce

Interface LifecycleMapper<KeyIn,ValueIn,KeyOut,ValueOut>

Type Parameters:

KeyIn - type of key used in the KeyValueSource

ValueIn - type of value used in the KeyValueSource

KeyOut - key type for mapped results

ValueOut - value type for mapped results

All Superinterfaces:

Mapper<KeyIn,ValueIn,KeyOut,ValueOut>, Serializable

All Known Implementing Classes:

LifecycleMapperAdapter

@Beta
public interface LifecycleMapper<KeyIn,ValueIn,KeyOut,ValueOut>
extends Mapper<KeyIn,ValueIn,KeyOut,ValueOut>

The LifecycleMapper interface is a more sophisticated version of Mapper normally used for more complex algorithms with a need for initialization and finalization.

The behavior is the same as for Mapper, but initialize(Context) is called before calling Mapper.map(Object, Object, Context) for the first time to prepare the mapper instance and maybe already emit some values. After all mapping calls are finished, finalized(Context) is called and here is another possibility to emit additional key-value pairs.

Since:

3.2

Method Summary

Methods

Modifier and Type	Method and Description
void	finalized(Context<KeyOut,ValueOut> context) This method is called after the Mapper.map(Object, Object, Context) method is executed for every value and can be used to finalize the internal state of the mapper or to emit a special value.
void	initialize(Context<KeyOut,ValueOut> context) This method is called before the Mapper.map(Object, Object, Context) method is executed for every value and can be used to initialize the internal state of the mapper or to emit a special value.

Methods inherited from interface com.hazelcast.mapreduce.Mapper

map

Method Detail

initialize

void initialize(Context<KeyOut,ValueOut> context)

This method is called before the Mapper.map(Object, Object, Context) method is executed for every value and can be used to initialize the internal state of the mapper or to emit a special value.

Parameters:

context - Context to be used for emitting values

finalized

void finalized(Context<KeyOut,ValueOut> context)

This method is called after the Mapper.map(Object, Object, Context) method is executed for every value and can be used to finalize the internal state of the mapper or to emit a special value.

Parameters:

context - Context to be used for emitting values