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HSQLDB example source code file (StopWatch.java)

This example HSQLDB source code file (StopWatch.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - HSQLDB tags/keywords

stopwatch, stopwatch, string, string

The HSQLDB StopWatch.java source code

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


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
     * attribute to the current value of System.currentTimeMillis() and setting
     * the <code>running attribute to true.
     */
    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 attribute the elapsed time since the last transition
     * from stopped to running state and sets the <code>running 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 + "]";
    }
}

Other HSQLDB examples (source code examples)

Here is a short list of links related to this HSQLDB StopWatch.java source code file:

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