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, 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

Constructor Summary

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

Method Summary

Object	aggregate(Set setEntries) Process a set of InvocableMap.Entry objects in order to produce an aggregated result.
Object	aggregateResults(Collection collResults) Aggregate the results of the parallel aggregations.
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(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(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 Object aggregate(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.

Specified by:

getParallelAggregator in interface InvocableMap.ParallelAwareAggregator

Returns:

the aggregator that will be run in parallel

aggregateResults

public Object aggregateResults(Collection collResults)

Aggregate the results of the parallel aggregations.

Specified by:

aggregateResults in interface InvocableMap.ParallelAwareAggregator

Returns:

the aggregation of the parallel aggregation results

readExternal

public void readExternal(DataInput in)
                  throws 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:

IOException - if an I/O exception occurs

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

writeExternal

public void writeExternal(DataOutput out)
                   throws 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:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws 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:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws 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:

IOException - if an I/O error occurs