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package org.hsqldb.lib;/** * Provides the programatic analog of a physical stop watch. <p> * * The watch can be started, stopped and zeroed and can be queried for * elapsed running time.  The watch accumulates elapsed time over starts * and stops such that only the time actually spent running is recorded. * If the watch is zeroed, then the accumulated time is discarded and * the watch starts again with zero acumulated time. <p> * * @author boucherb@users * @version 1.7.2 * @since 1.7.2 */public class StopWatch {    /**     * The last time this object made the transition     * from stopped to running state, as reported     * by System.currentTimeMillis().     */    private long startTime;    private long lastStart;    /**     * The accumulated running time of this object since     * it was last zeroed.     */    private long total;    /** Flags if this object is started or stopped. */    boolean running = false;    /** Creates, zeros, and starts a new StopWatch */    public StopWatch() {        this(true);    }    /** Creates, zeros, and starts a new StopWatch */    public StopWatch(boolean start) {        if (start) {            start();        }    }    /**     * Retrieves the accumulated time this object has spent running since     * it was last zeroed.     * @return the accumulated time this object has spent running since     * it was last zeroed.     */    public long elapsedTime() {        if (running) {            return total + System.currentTimeMillis() - startTime;        } else {            return total;        }    }    /**     * Retrieves the accumulated time this object has spent running since     * it was last started.     * @return the accumulated time this object has spent running since     * it was last started.     */    public long currentElapsedTime() {        if (running) {            return System.currentTimeMillis() - startTime;        } else {            return 0;        }    }    /** Zeros accumulated running time and restarts this object. */    public void zero() {        total = 0;        start();    }    /**     * Ensures that this object is in the running state.  If this object is not     * running, then the call has the effect of setting the <code>startTime</code>     * attribute to the current value of System.currentTimeMillis() and setting     * the <code>running</code> attribute to <code>true</code>.     */    public void start() {        startTime = System.currentTimeMillis();        running   = true;    }    /**     * Ensures that this object is in the stopped state.  If this object is     * in the running state, then this has the effect of adding to the     * <code>total</code> attribute the elapsed time since the last transition     * from stopped to running state and sets the <code>running</code> attribute     * to false. If this object is not in the running state, this call has no     * effect.     */    public void stop() {        if (running) {            total   += System.currentTimeMillis() - startTime;            running = false;        }    }    public void mark() {        stop();        start();    }    /**     * Retrieves prefix + " in " + elapsedTime() + " ms."     * @param prefix The string to use as a prefix     * @return prefix + " in " + elapsedTime() + " ms."     */    public String elapsedTimeToMessage(String prefix) {        return prefix + " in " + elapsedTime() + " ms.";    }    /**     * Retrieves prefix + " in " + elapsedTime() + " ms."     * @param prefix The string to use as a prefix     * @return prefix + " in " + elapsedTime() + " ms."     */    public String currentElapsedTimeToMessage(String prefix) {        return prefix + " in " + currentElapsedTime() + " ms.";    }    /**     * Retrieves the internal state of this object, as a String.     *     * The retreived value is:     *     * <pre>     *    super.toString() +     *    "[running=" +     *    running +     *    ", startTime=" +     *    startTime +     *    ", total=" +     *    total + "]";     * </pre>     * @return the state of this object, as a String     */    public String toString() {        return super.toString() + "[running=" + running + ", startTime="               + startTime + ", total=" + total + "]";    }}