net.sf.jagg
Class CountAggregator

java.lang.Object
  net.sf.jagg.Aggregator
      net.sf.jagg.CountAggregator

public class CountAggregator
extends Aggregator

This class represents the "count" aggregator over any values.

Since:

0.1.0

Author:

Randy Gettman

Field Summary

static java.lang.String

COUNT_ALL Special pseudo-property indicating "count all", even nulls.

Fields inherited from class net.sf.jagg.Aggregator

PROP_SELF

Constructor Summary

CountAggregator(java.lang.String property)
Constructs an CountAggregator that operates on the specified property.

Method Summary

void	init() Initialize the count to zero.
void	iterate(java.lang.Object value) Count the property if its value is non-null.
void	merge(Aggregator agg) Merge the given Aggregator into this one by adding the counts.
CountAggregator	replicate() Returns an uninitialized copy of this Aggregator object, with the same property(ies) to analyze.
java.lang.Long	terminate() Return the count.

Methods inherited from class net.sf.jagg.Aggregator

equals, getAggregator, getAggregator, getProperty, getValueFromProperty, hashCode, isInUse, setInUse, setProperty, terminateDoubleDouble, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

COUNT_ALL

public static final java.lang.String COUNT_ALL

Special pseudo-property indicating "count all", even nulls.

See Also:

Constant Field Values

Constructor Detail

CountAggregator

public CountAggregator(java.lang.String property)

Constructs an CountAggregator that operates on the specified property.

Parameters:

property - Count this property's values.

Method Detail

replicate

public CountAggregator replicate()

Returns an uninitialized copy of this Aggregator object, with the same property(ies) to analyze.

Specified by:

replicate in class Aggregator

Returns:

An uninitialized copy of this Aggregator object.

init

public void init()

Initialize the count to zero.

Specified by:

init in class Aggregator

iterate

public void iterate(java.lang.Object value)

Count the property if its value is non-null. If the property is COUNT_ALL, then always count it, null or not.

Specified by:

iterate in class Aggregator

Parameters:

value - The value to aggregate.

See Also:

COUNT_ALL

merge

public void merge(Aggregator agg)

Merge the given Aggregator into this one by adding the counts.

Specified by:

merge in class Aggregator

Parameters:

agg - The Aggregator to merge into this one.

terminate

public java.lang.Long terminate()

Return the count.

Specified by:

terminate in class Aggregator

Returns:

The count as a Long.