com.hazelcast.aggregation.impl

Class CountAggregator<I>

java.lang.Object

com.hazelcast.aggregation.Aggregator<I,R>

com.hazelcast.aggregation.impl.AbstractAggregator<I,Object,Long>

com.hazelcast.aggregation.impl.CountAggregator<I>

All Implemented Interfaces:

DataSerializable, IdentifiedDataSerializable, Serializable

public final class CountAggregator<I>
extends AbstractAggregator<I,Object,Long>
implements IdentifiedDataSerializable

See Also:

Serialized Form

Field Summary

Fields inherited from class com.hazelcast.aggregation.impl.AbstractAggregator

attributePath

Constructor Summary

Constructors

Constructor and Description
CountAggregator()
CountAggregator(String attributePath)

Method Summary

Modifier and Type	Method and Description
void	accumulateExtracted(I entry, Object value) Accumulates a single extracted value.
Long	aggregate() Returns the result of the aggregation.
void	combine(Aggregator aggregator) Incorporates the intermediary result of the given aggregator to this instance of the aggregator.
int	getFactoryId() Returns DataSerializableFactory factory ID for this class.
int	getId() Returns type identifier for this class.
void	readData(ObjectDataInput in) Reads fields from the input stream
void	writeData(ObjectDataOutput out) Writes object fields to output stream

Methods inherited from class com.hazelcast.aggregation.impl.AbstractAggregator

accumulate

Methods inherited from class com.hazelcast.aggregation.Aggregator

onAccumulationFinished, onCombinationFinished

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CountAggregator

public CountAggregator()

CountAggregator

public CountAggregator(String attributePath)

Method Detail

accumulateExtracted

public void accumulateExtracted(I entry,
                                Object value)

Description copied from class: AbstractAggregator

Accumulates a single extracted value. This method may be called multiple times per accumulated entry if the attributePath contains [any] operator.

Specified by:

accumulateExtracted in class AbstractAggregator<I,Object,Long>

Parameters:

entry - The entry containing the value.

value - If attributePath is not null the methods accumulates the value extracted from the attributePath. If attributePath is null and the input object is a Map.Entry the method accumulates Map.Entry.getValue().

combine

public void combine(Aggregator aggregator)

Description copied from class: Aggregator

Incorporates the intermediary result of the given aggregator to this instance of the aggregator. The given aggregator has to be of the same class as the one that the method is being called on. Enables merging the intermediary state from a given aggregator. It is used when the aggregation is split into a couple of aggregators.

Specified by:

combine in class Aggregator<I,Long>

Parameters:

aggregator - aggregator providing intermediary results to be combined into the results of this aggregator. The given aggregator has to be of the same class as the one that the method is being called on.

aggregate

public Long aggregate()

Description copied from class: Aggregator

Returns the result of the aggregation. The result may be calculated in this call or cached by the aggregator.

Specified by:

aggregate in class Aggregator<I,Long>

Returns:

returns the result of the aggregation.

getFactoryId

public int getFactoryId()

Description copied from interface: IdentifiedDataSerializable

Returns DataSerializableFactory factory ID for this class.

Specified by:

getFactoryId in interface IdentifiedDataSerializable

Returns:

factory ID

getId

public int getId()

Description copied from interface: IdentifiedDataSerializable

Returns type identifier for this class. It should be unique per DataSerializableFactory.

Specified by:

getId in interface IdentifiedDataSerializable

Returns:

type ID

writeData

public void writeData(ObjectDataOutput out)
               throws IOException

Description copied from interface: DataSerializable

Writes object fields to output stream

Specified by:

writeData in interface DataSerializable

Parameters:

out - output

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the output stream has been closed.

readData

public void readData(ObjectDataInput in)
              throws IOException

Description copied from interface: DataSerializable

Reads fields from the input stream

Specified by:

readData in interface DataSerializable

Parameters:

in - input

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the input stream has been closed.