/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
package com.espertech.esper.epl.agg.aggregator;
/**
* Average that generates double-typed numbers.
*/
public class AggregatorAvg implements AggregationMethod {
protected double sum;
protected long numDataPoints;
public void clear() {
sum = 0;
numDataPoints = 0;
}
public void enter(Object object) {
if (object == null) {
return;
}
numDataPoints++;
sum += ((Number) object).doubleValue();
}
public void leave(Object object) {
if (object == null) {
return;
}
if (numDataPoints <= 1) {
clear();
} else {
numDataPoints--;
sum -= ((Number) object).doubleValue();
}
}
public Object getValue() {
if (numDataPoints == 0) {
return null;
}
return sum / numDataPoints;
}
}