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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

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 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(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.
  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 results of the parallel aggregations.
  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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