AggregatorAvgBigDecimal.java

/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * 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;

import java.math.BigDecimal;
import java.math.BigInteger;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Average that generates a BigDecimal numbers.
 */
public class AggregatorAvgBigDecimal implements AggregationMethod
{
    private static final Log log = LogFactory.getLog(AggregatorAvgBigDecimal.class);
    protected BigDecimal sum;
    protected long numDataPoints;

    /**
     * Ctor.
     */
    public AggregatorAvgBigDecimal()
    {
        sum = new BigDecimal(0.0);
    }

    public void clear()
    {
        sum = new BigDecimal(0.0);
        numDataPoints = 0;
    }

    public void enter(Object object)
    {
        if (object == null)
        {
            return;
        }
        numDataPoints++;
        if (object instanceof BigInteger)
        {
            sum = sum.add(new BigDecimal((BigInteger) object));
            return;
        }
        sum = sum.add((BigDecimal) object);
    }

    public void leave(Object object)
    {
        if (object == null)
        {
            return;
        }
        numDataPoints--;
        if (object instanceof BigInteger)
        {
            sum = sum.subtract(new BigDecimal((BigInteger) object));
            return;
        }
        sum = sum.subtract((BigDecimal) object);
    }

    public Object getValue()
    {
        if (numDataPoints == 0)
        {
            return null;
        }
        try
        {
            return sum.divide(new BigDecimal(numDataPoints));
        }
        catch (ArithmeticException ex)
        {
            log.error("Error computing avg aggregation result: " + ex.getMessage(), ex);
            return new BigDecimal(0);
        }
    }

    public Class getValueType()
    {
        return Double.class;
    }
}