differentialset.java

这是一个以JAVA编写的程序,本人还没有试过,是一个简单的温度控制系统

package net.sf.dz.controller;

import java.util.Iterator;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 * Data set supporting the differential calculation.
 *
 * @author Copyright &copy; <a href="mailto:[e-mail]"> Vadim Tkachenko</a> 2001-2002
 * @version $Id: DifferentialSet.java,v 1.3 2004/06/28 20:35:46 vtt Exp $
 */
public class DifferentialSet extends DataSet {

    /**
     * Create the instance.
     *
     * @param differentialTime Differential time, milliseconds. Data
     * elements older than this are expired.
     */
    public DifferentialSet(final long differentialTime) {

        super(differentialTime);
    }

    /**
     * Get the differential starting with the first data element available
     * and ending with the last data element available.
     *
     * <p>
     *
     * Differentiation time must have been taken care of by {@link
     * DataSet#expire expiration}.
     *
     * @return A differential value.
     */
    public final double getDifferential() {

        if (size() < 2) {

            // Nothing to compare yet

            return 0;
        }

        long startTime = System.currentTimeMillis();

        try {

            // The following line will throw the NoSuchElementException if
            // the dataSet is empty. It is possible to check the size, but
            // handling the exception is more efficient because happens just
            // once - at the startup, or when there was an interruption in
            // the data sequence longer than the expiration interval and all
            // the data elements were expired.

            Iterator i = iterator();
            Long trailerKey = (Long) i.next();

            SortedMap resultSet = new TreeMap();

            while (i.hasNext()) {

                double trailerValue = get(trailerKey.longValue());
                Long currentKey = (Long) i.next();
                double currentValue = get(currentKey.longValue());

                long start = trailerKey.longValue();
                long stop = currentKey.longValue();

                double diff = (currentValue - trailerValue) / (currentKey.longValue() - trailerKey.longValue());

                resultSet.put(new Long(start + ((start + stop) / 2)), new Double(diff));

                trailerKey = currentKey;
            }

            double result = 0;

            i = resultSet.keySet().iterator();
            trailerKey = (Long) i.next();

            while (i.hasNext()) {

                double trailerValue = ((Double) resultSet.get(trailerKey)).doubleValue();
                Long currentKey = (Long) i.next();
                double currentValue = ((Double) resultSet.get(currentKey)).doubleValue();

                double diff = ((currentValue + trailerValue) / 2) * (currentKey.longValue() - trailerKey.longValue());

                result += diff;

                trailerKey = currentKey;
            }

            return result;

        } finally {

            //System.err.println("getDifferential@" + hashCode() + "," + dataSet.size() + ": " + (System.currentTimeMillis() - startTime));
        }
    }
}