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com.tangosol.util.aggregator
Class Count

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.aggregator.Count

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryAggregator, InvocableMap.ParallelAwareAggregator, java.io.Serializable

public class Count

extends Base

implements InvocableMap.ParallelAwareAggregator, ExternalizableLite, PortableObject

Calculates a number of values in an entry set.

Since:

Coherence 3.1

Author:

gg 2005.09.05

Nested Class Summary

Nested classes/interfaces inherited from interface com.tangosol.util.InvocableMap.ParallelAwareAggregator

InvocableMap.ParallelAwareAggregator.PartialResultAggregator

Constructor Summary

Count()
Default constructor (necessary for the ExternalizableLite interface).

Method Summary

java.lang.Object	aggregate(java.util.Set setEntries) Process a set of InvocableMap.Entry objects in order to produce an aggregated result.
java.lang.Object	aggregateResults(java.util.Collection collResults) Aggregate the partial results of the parallel aggregations into a final result.
InvocableMap.EntryAggregator	getParallelAggregator() Get an aggregator that can take the place of this aggregator in situations in which the InvocableMap can aggregate in parallel.
void	readExternal(java.io.DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	writeExternal(java.io.DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Constructor Detail

Count

public Count()

Default constructor (necessary for the ExternalizableLite interface).

Method Detail

aggregate

public java.lang.Object aggregate(java.util.Set setEntries)

Process a set of InvocableMap.Entry objects in order to produce an aggregated result.

Specified by:

aggregate in interface InvocableMap.EntryAggregator

Parameters:

setEntries - a Set of read-only InvocableMap.Entry objects to aggregate

Returns:

the aggregated result from processing the entries

getParallelAggregator

public InvocableMap.EntryAggregator getParallelAggregator()

Get an aggregator that can take the place of this aggregator in situations in which the InvocableMap can aggregate in parallel.

If the returned aggregator is a InvocableMap.ParallelAwareAggregator.PartialResultAggregator, the partial results of the parallel aggregation may be further aggregated where optimal.

Specified by:

getParallelAggregator in interface InvocableMap.ParallelAwareAggregator

Returns:

the aggregator that will be run in parallel

aggregateResults

public java.lang.Object aggregateResults(java.util.Collection collResults)

Aggregate the partial results of the parallel aggregations into a final result.

Specified by:

aggregateResults in interface InvocableMap.ParallelAwareAggregator

Parameters:

collResults - the parallel aggregation results

Returns:

the aggregation of the parallel aggregation results

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

java.io.IOException - if an I/O exception occurs

java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

java.io.IOException - if an I/O error occurs

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