Java/Development Class/Timer
Содержание
- 1 A simple implementation of the Java 1.3 java.util.Timer API
- 2 Class encapsulating timer functionality
- 3 Create a scheduled task using timer
- 4 Create a Timer object
- 5 extends TimerTask to create your own task
- 6 Pause and start a timer task
- 7 Schedule a task by using Timer and TimerTask.
- 8 Scheduling a Timer Task to Run at a Certain Time
- 9 Scheduling a Timer Task to Run Repeatedly
- 10 Swing also provide a Timer class. A Timer object will send an ActionEvent to the registered ActionListener.
- 11 Timeout Observer
- 12 Timer and TimerTask Classes
- 13 Timer Schedule a task that executes once every second
- 14 Timer Skipping Beep
- 15 Timer utilities
- 16 Use java.util.Timer to schedule a task to execute once 5 seconds have passed
A simple implementation of the Java 1.3 java.util.Timer API
<source lang="java">
/*
* Copyright (c) 2004 David Flanagan. All rights reserved. * This code is from the book Java Examples in a Nutshell, 3nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose, * including teaching and use in open-source projects. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book, * please visit http://www.davidflanagan.ru/javaexamples3. */
import java.util.ruparator; import java.util.Date; import java.util.SortedSet; import java.util.TreeSet; abstract class TimerTask implements Runnable {
boolean cancelled = false; // Has it been cancelled?
long nextTime = -1; // When is it next scheduled?
long period; // What is the execution interval
boolean fixedRate; // Fixed-rate execution?
protected TimerTask() {
}
/**
* Cancel the execution of the task. Return true if it was actually running,
* or false if it was already cancelled or never scheduled.
*/
public boolean cancel() {
if (cancelled)
return false; // Already cancelled;
cancelled = true; // Cancel it
if (nextTime == -1)
return false; // Never scheduled;
return true;
}
/**
* When it the timer scheduled to execute? The run() method can use this to
* see whether it was invoked when it was supposed to be
*/
public long scheduledExecutionTime() {
return nextTime;
}
/**
* Subclasses must override this to provide that code that is to be run. The
* Timer class will invoke this from its internal thread.
*/
public abstract void run();
// This method is used by Timer to tell the Task how it is scheduled.
void schedule(long nextTime, long period, boolean fixedRate) {
this.nextTime = nextTime;
this.period = period;
this.fixedRate = fixedRate;
}
// This will be called by Timer after Timer calls the run method.
boolean reschedule() {
if (period == 0 || cancelled)
return false; // Don"t run it again
if (fixedRate)
nextTime += period;
else
nextTime = System.currentTimeMillis() + period;
return true;
}
} /**
* This class is a simple implementation of the Java 1.3 java.util.Timer API */
public class Timer {
// This sorted set stores the tasks that this Timer is responsible for.
// It uses a comparator to sort the tasks by scheduled execution time.
SortedSet tasks = new TreeSet(new Comparator() {
public int compare(Object a, Object b) {
return (int) (((TimerTask) a).nextTime - ((TimerTask) b).nextTime);
}
public boolean equals(Object o) {
return this == o;
}
});
// This is the thread the timer uses to execute the tasks.
// The TimerThread class is defined below.
TimerThread timer;
/** This constructor create a Timer that does not use a daemon thread */
public Timer() {
this(false);
}
/** The main constructor: the internal thread is a daemon if specified */
public Timer(boolean isDaemon) {
timer = new TimerThread(isDaemon); // TimerThread is defined below
timer.start(); // Start the thread running
}
/** Stop the timer thread, and discard all scheduled tasks */
public void cancel() {
synchronized (tasks) { // Only one thread at a time!
timer.pleaseStop(); // Set a flag asking the thread to stop
tasks.clear(); // Discard all tasks
tasks.notify(); // Wake up the thread if it is in wait().
}
}
/** Schedule a single execution after delay milliseconds */
public void schedule(TimerTask task, long delay) {
task.schedule(System.currentTimeMillis() + delay, 0, false);
schedule(task);
}
/** Schedule a single execution at the specified time */
public void schedule(TimerTask task, Date time) {
task.schedule(time.getTime(), 0, false);
schedule(task);
}
/** Schedule a periodic execution starting at the specified time */
public void schedule(TimerTask task, Date firstTime, long period) {
task.schedule(firstTime.getTime(), period, false);
schedule(task);
}
/** Schedule a periodic execution starting after the specified delay */
public void schedule(TimerTask task, long delay, long period) {
task.schedule(System.currentTimeMillis() + delay, period, false);
schedule(task);
}
/**
* Schedule a periodic execution starting after the specified delay. Schedule
* fixed-rate executions period ms after the start of the last. Instead of
* fixed-interval executions measured from the end of the last.
*/
public void scheduleAtFixedRate(TimerTask task, long delay, long period) {
task.schedule(System.currentTimeMillis() + delay, period, true);
schedule(task);
}
/** Schedule a periodic execution starting after the specified time */
public void scheduleAtFixedRate(TimerTask task, Date firstTime, long period) {
task.schedule(firstTime.getTime(), period, true);
schedule(task);
}
// This internal method adds a task to the sorted set of tasks
void schedule(TimerTask task) {
synchronized (tasks) { // Only one thread can modify tasks at a time!
tasks.add(task); // Add the task to the sorted set of tasks
tasks.notify(); // Wake up the thread if it is waiting
}
}
/**
* This inner class defines the thread that runs each of the tasks at their
* scheduled times
*/
class TimerThread extends Thread {
// This flag is will be set true to tell the thread to stop running.
// Note that it is declared volatile, which means that it may be
// changed asynchronously by another thread, so threads must always
// read its current value, and not used a cached version.
volatile boolean stopped = false;
// The constructor
TimerThread(boolean isDaemon) {
setDaemon(isDaemon);
}
// Ask the thread to stop by setting the flag above
void pleaseStop() {
stopped = true;
}
// This is the body of the thread
public void run() {
TimerTask readyToRun = null; // Is there a task to run right now?
// The thread loops until the stopped flag is set to true.
while (!stopped) {
// If there is a task that is ready to run, then run it!
if (readyToRun != null) {
if (readyToRun.cancelled) { // If it was cancelled, skip.
readyToRun = null;
continue;
}
// Run the task.
readyToRun.run();
// Ask it to reschedule itself, and if it wants to run
// again, then insert it back into the set of tasks.
if (readyToRun.reschedule())
schedule(readyToRun);
// We"ve run it, so there is nothing to run now
readyToRun = null;
// Go back to top of the loop to see if we"ve been stopped
continue;
}
// Now acquire a lock on the set of tasks
synchronized (tasks) {
long timeout; // how many ms "till the next execution?
if (tasks.isEmpty()) { // If there aren"t any tasks
timeout = 0; // Wait "till notified of a new task
} else {
// If there are scheduled tasks, then get the first one
// Since the set is sorted, this is the next one.
TimerTask t = (TimerTask) tasks.first();
// How long "till it is next run?
timeout = t.nextTime - System.currentTimeMillis();
// Check whether it needs to run now
if (timeout <= 0) {
readyToRun = t; // Save it as ready to run
tasks.remove(t); // Remove it from the set
// Break out of the synchronized section before
// we run the task
continue;
}
}
// If we get here, there is nothing ready to run now,
// so wait for time to run out, or wait "till notify() is
// called when something new is added to the set of tasks.
try {
tasks.wait(timeout);
} catch (InterruptedException e) {
}
// When we wake up, go back up to the top of the while loop
}
}
}
}
/** This inner class defines a test program */
public static class Test {
public static void main(String[] args) {
final TimerTask t1 = new TimerTask() { // Task 1: print "boom"
public void run() {
System.out.println("boom");
}
};
final TimerTask t2 = new TimerTask() { // Task 2: print "BOOM"
public void run() {
System.out.println("\tBOOM");
}
};
final TimerTask t3 = new TimerTask() { // Task 3: cancel the tasks
public void run() {
t1.cancel();
t2.cancel();
}
};
// Create a timer, and schedule some tasks
final Timer timer = new Timer();
timer.schedule(t1, 0, 500); // boom every .5sec starting now
timer.schedule(t2, 2000, 2000); // BOOM every 2s, starting in 2s
timer.schedule(t3, 5000); // Stop them after 5 seconds
// Schedule a final task: starting in 5 seconds, count
// down from 5, then destroy the timer, which, since it is
// the only remaining thread, will cause the program to exit.
timer.scheduleAtFixedRate(new TimerTask() {
public int times = 5;
public void run() {
System.out.println(times--);
if (times == 0)
timer.cancel();
}
}, 5000, 500);
}
}
}
</source>
Class encapsulating timer functionality
<source lang="java">
/*
* Copyright (c) 2003 - 2007 OpenSubsystems s.r.o. Slovak Republic. All rights reserved. * * Project: OpenSubsystems * * $Id: MyTimer.java,v 1.5 2007/01/07 06:14:00 bastafidli Exp $ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/**
* Class encapsulating timer functionality. * * @version $Id: MyTimer.java,v 1.5 2007/01/07 06:14:00 bastafidli Exp $ * @author Miro Halas * @code.reviewer Miro Halas * @code.reviewed Initial revision */
public class MyTimer {
// Attributes ///////////////////////////////////////////////////////////////
/**
* Remeber start time here.
*/
private long m_lStartTime;
/**
* Remeber stop time here.
*/
private long m_lStopTime;
// Constructors /////////////////////////////////////////////////////////////
/**
* Default constructor.
* Starts counting fro the moment it is cosntructed.
*/
public MyTimer(
)
{
reset();
}
// Logic ////////////////////////////////////////////////////////////////////
/**
* @return long - start time;
*/
public long getStartTime()
{
return m_lStartTime;
}
/**
* @return - stop time;
*/
public long getStopTime()
{
return m_lStopTime;
}
/**
* Reset the counter and start counting from scratch.
*/
public void reset(
)
{
m_lStartTime = System.currentTimeMillis();
m_lStopTime = 0;
}
/**
* Stop the timer.
*/
public void stop(
)
{
m_lStopTime = System.currentTimeMillis();
}
/**
* Get timer duration (the timer doesn"t stop) in milliseconds.
*
* @return long - difference between stop and start time.
*/
public long getDuration(
)
{
long lStopTime;
if (m_lStopTime == 0)
{
lStopTime = System.currentTimeMillis();
}
else
{
lStopTime = m_lStopTime;
}
return lStopTime - m_lStartTime;
}
/**
* Print the state of the timer without stopping it.
* @return String - timing information
*/
public String toString(
)
{
long lTotalMS = getDuration();
long lMS = lTotalMS % 1000;
long lTotalSecs = lTotalMS / 1000;
long lSecs = lTotalSecs % 60;
long lTotalMins = lTotalSecs / 60;
long lMinutes = lTotalMins % 60;
long lHours = lTotalMins / 60;
StringBuffer sbBuffer = new StringBuffer();
if (lHours > 0)
{
sbBuffer.append(lHours);
sbBuffer.append(":");
sbBuffer.append(lMinutes);
sbBuffer.append(":");
sbBuffer.append(lSecs);
sbBuffer.append(".");
sbBuffer.append(lMS);
}
else if (lMinutes > 0)
{
sbBuffer.append(lMinutes);
sbBuffer.append(":");
sbBuffer.append(lSecs);
sbBuffer.append(".");
sbBuffer.append(lMS);
}
else if (lSecs > 0)
{
sbBuffer.append(lSecs);
sbBuffer.append(".");
sbBuffer.append(lMS);
sbBuffer.append(" seconds");
}
else
{
sbBuffer.append(lMS);
sbBuffer.append(" ms");
}
return sbBuffer.toString();
}
}
</source>
Create a scheduled task using timer
<source lang="java">
import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Timer; import java.util.TimerTask; public class Main extends TimerTask {
private DateFormat formatter = new SimpleDateFormat("hh:mm:ss a");
public static void main(String[] args) {
TimerTask task = new Main();
Timer timer = new Timer();
timer.scheduleAtFixedRate(task, new Date(), 1000);
}
public void run() {
System.out.println(formatter.format(new Date()));
}
}
</source>
Create a Timer object
<source lang="java">
import java.util.Timer; import java.util.TimerTask; public class Main {
Timer timer;
public Main(int seconds) {
timer = new Timer();
timer.schedule(new ToDoTask(), seconds * 1000);
}
class ToDoTask extends TimerTask {
public void run() {
System.out.println("working");
timer.cancel();
}
}
public static void main(String args[]) {
new Main(5);
}
}
</source>
extends TimerTask to create your own task
<source lang="java">
import java.io.DataOutputStream; import java.io.IOException; import java.io.OutputStream; import java.util.TimerTask; class MyTask extends TimerTask {
private DataOutputStream out;
public MyTask(OutputStream dest) {
out = new DataOutputStream(dest);
}
public void run() {
try {
out.writeInt(1);
out.writeUTF("asdf");
} catch (IOException e) {
e.printStackTrace();
}
}
}
</source>
Pause and start a timer task
<source lang="java">
import java.util.Timer; import java.util.TimerTask; class MyTask extends TimerTask {
int counter;
public MyTask() {
counter = 0;
}
public void run() {
counter++;
System.out.println("Ring " + counter);
}
public int getCount() {
return counter;
}
} public class Main {
private boolean running;
private MyTask task;
private Timer timer;
public Main() {
timer = new Timer(true);
}
public boolean isRinging() {
return running;
}
public void startRinging() {
running = true;
task = new MyTask();
timer.scheduleAtFixedRate(task, 0, 3000);
}
public void doIt() {
running = false;
System.out.println(task.getCount() + " times");
task.cancel();
}
public static void main(String[] args) {
Main phone = new Main();
phone.startRinging();
try {
System.out.println("started running...");
Thread.sleep(20000);
} catch (InterruptedException e) {
}
phone.doIt();
}
}
</source>
Schedule a task by using Timer and TimerTask.
<source lang="java">
import java.util.Date; import java.util.Timer; import java.util.TimerTask; class AutoTask extends TimerTask {
AutoTask() {
}
public void run() {
System.out.println(new Date());
}
} public class Main {
public static void main(String args[]) {
AutoTask myTask = new AutoTask();
Timer bkTimer = new Timer();
bkTimer.schedule(myTask, 2000, 2000);
for (int i = 0; i < 5; i++) {
try {
Thread.sleep(2100);
} catch (InterruptedException exc) {
}
}
bkTimer.cancel();
}
}
</source>
Scheduling a Timer Task to Run at a Certain Time
<source lang="java">
import java.sql.Date; import java.util.Timer; import java.util.TimerTask; public class Main {
public static void main(String[] argv) throws Exception {
Date timeToRun = new Date(System.currentTimeMillis() + numberOfMillisecondsInTheFuture);
Timer timer = new Timer();
timer.schedule(new TimerTask() {
public void run() {
System.out.println("doing");
}
}, timeToRun);
}
}
</source>
Scheduling a Timer Task to Run Repeatedly
<source lang="java">
import java.util.Timer; import java.util.TimerTask; public class Main {
public static void main(String[] argv) throws Exception {
int delay = 5000; // delay for 5 sec.
int period = 1000; // repeat every sec.
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
System.out.println("doing");
}
}, delay, period);
}
}
</source>
Swing also provide a Timer class. A Timer object will send an ActionEvent to the registered ActionListener.
<source lang="java">
import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Timer; public class Main implements ActionListener {
Timer t = new Timer(1000, this);
Main() {
t.start();
}
public void actionPerformed(ActionEvent e) {
System.out.println("working");
}
public static void main(String args[]) {
Main main = new Main();
}
}
</source>
Timeout Observer
<source lang="java">
/*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */
import java.util.Enumeration; import java.util.Vector; /**
* Generalization of ExecuteWatchdog
*
* @see org.apache.rumons.exec.ExecuteWatchdog
*/
public class Watchdog implements Runnable {
private Vector observers = new Vector(1);
private final long timeout;
private boolean stopped = false;
public Watchdog(final long timeout) {
if (timeout < 1) {
throw new IllegalArgumentException("timeout must not be less than 1.");
}
this.timeout = timeout;
}
public void addTimeoutObserver(final TimeoutObserver to) {
observers.addElement(to);
}
public void removeTimeoutObserver(final TimeoutObserver to) {
observers.removeElement(to);
}
protected final void fireTimeoutOccured() {
Enumeration e = observers.elements();
while (e.hasMoreElements()) {
((TimeoutObserver) e.nextElement()).timeoutOccured(this);
}
}
public synchronized void start() {
stopped = false;
Thread t = new Thread(this, "WATCHDOG");
t.setDaemon(true);
t.start();
}
public synchronized void stop() {
stopped = true;
notifyAll();
}
public synchronized void run() {
final long until = System.currentTimeMillis() + timeout;
long now;
while (!stopped && until > (now = System.currentTimeMillis())) {
try {
wait(until - now);
} catch (InterruptedException e) {
}
}
if (!stopped) {
fireTimeoutOccured();
}
}
} /**
* Interface for classes that want to be notified by Watchdog. * * @see org.apache.rumons.exec.Watchdog */
interface TimeoutObserver {
/** * Called when the watchdow times out. * * @param w * the watchdog that timed out. */ void timeoutOccured(Watchdog w);
}
</source>
Timer and TimerTask Classes
<source lang="java">
import java.util.Timer; import java.util.TimerTask; class GCTask extends TimerTask {
public void run() {
System.out.println("Running the scheduled task...");
System.gc();
}
} public class Main {
public static void main(String[] args) {
Timer timer = new Timer();
GCTask task = new GCTask();
timer.schedule(task, 5000, 5000);
int counter = 1;
while (true) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
}
}
}
}
</source>
Timer Schedule a task that executes once every second
<source lang="java">
/* From http://java.sun.ru/docs/books/tutorial/index.html */ /*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.awt.Toolkit; import java.util.Timer; import java.util.TimerTask; /**
* Schedule a task that executes once every second. */
public class AnnoyingBeep {
Toolkit toolkit;
Timer timer;
public AnnoyingBeep() {
toolkit = Toolkit.getDefaultToolkit();
timer = new Timer();
timer.schedule(new RemindTask(), 0, //initial delay
1 * 1000); //subsequent rate
}
class RemindTask extends TimerTask {
int numWarningBeeps = 3;
public void run() {
if (numWarningBeeps > 0) {
toolkit.beep();
System.out.println("Beep!");
numWarningBeeps--;
} else {
toolkit.beep();
System.out.println("Time"s up!");
//timer.cancel(); //Not necessary because we call System.exit
System.exit(0); //Stops the AWT thread (and everything else)
}
}
}
public static void main(String args[]) {
System.out.println("About to schedule task.");
new AnnoyingBeep();
System.out.println("Task scheduled.");
}
}
</source>
Timer Skipping Beep
<source lang="java">
/* From http://java.sun.ru/docs/books/tutorial/index.html */ /*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.awt.Toolkit; import java.util.Timer; import java.util.TimerTask; /**
* Schedule a task that executes once every second. */
public class SkippingBeep {
Toolkit toolkit;
Timer timer;
public SkippingBeep() {
toolkit = Toolkit.getDefaultToolkit();
timer = new Timer();
timer.scheduleAtFixedRate(new RemindTask(), 0, //initial delay
1 * 1000); //subsequent rate
}
class RemindTask extends TimerTask {
int numWarningBeeps = 3;
public void run() {
if (numWarningBeeps-- > 0) {
long time = System.currentTimeMillis();
if (time - scheduledExecutionTime() > 5) {
return;
}
//If it"s not too late, beep.
toolkit.beep();
System.out.println("Beep!");
} else {
toolkit.beep();
System.out.println("Time"s up!");
//timer.cancel(); //Not necessary because we call System.exit
System.exit(0); //Stops the AWT thread (and everything else)
}
}
}
public static void main(String args[]) {
System.out.println("About to schedule task.");
new SkippingBeep();
System.out.println("Task scheduled.");
}
}
</source>
Timer utilities
<source lang="java"> import java.util.Timer;
import java.util.TimerTask; /*
* UtilTimerDemo.java * * Created on May 2, 2007, 3:13 PM * * Copyright (c) 2007, Sun Microsystems, Inc * 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 TimingFramework project 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 THE COPYRIGHT * OWNER 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. */
/**
* * @author Chet */
public class UtilTimerDemo extends TimerTask {
private static long prevTime = 0;
private static long startTime = 0;
private static final long DELAY = 100;
private static final long DURATION = 5 * DELAY;
private static final long PROCESSING_TIME = 30;
private static final long INITIAL_PROCESSING_TIME = 2 * DELAY;
private static Timer timer = null;
private boolean firstTime = true;
private static boolean runningFixedRate = false;
/**
* This method will be called during every tick of the Timers.
* We insert an artificial delay each time, to simulate some processing.
* The first time through, this delay is greater than the delay between
* timing events, so that we can see how this hiccup is handled by
* fixed-rate and fixed-delay timers.
*/
public void run() {
long nowTime = System.currentTimeMillis();
long elapsedTime = nowTime - prevTime;
long totalTime = nowTime - startTime;
System.out.println("Elapsed time = " + elapsedTime);
if (totalTime > DURATION) {
timer.cancel();
}
prevTime = nowTime;
try {
if (firstTime) {
Thread.sleep(INITIAL_PROCESSING_TIME);
firstTime = false;
} else {
Thread.sleep(PROCESSING_TIME);
}
} catch (Exception e) {}
}
public UtilTimerDemo() {
firstTime = true;
}
public static void main(String[] args) {
// Start and run a fixed-delay timer
timer = new Timer();
startTime = prevTime = System.currentTimeMillis();
System.out.println("Fixed Delay Times");
timer.schedule(new UtilTimerDemo(), DELAY, DELAY);
// Sleep long enough to let the first timer finish
try {
Thread.sleep(DURATION*2);
} catch (Exception e) {}
// Start and run a fixed-rate timer
timer = new Timer();
startTime = prevTime = System.currentTimeMillis();
System.out.println("Fixed Rate Times");
timer.scheduleAtFixedRate(new UtilTimerDemo(), DELAY, DELAY);
}
}
</source>
Use java.util.Timer to schedule a task to execute once 5 seconds have passed
<source lang="java">
/* From http://java.sun.ru/docs/books/tutorial/index.html */ /*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import java.awt.Toolkit; import java.util.Timer; import java.util.TimerTask; /**
* Simple demo that uses java.util.Timer to schedule a task to execute once 5 * seconds have passed. */
public class ReminderBeep {
Toolkit toolkit;
Timer timer;
public ReminderBeep(int seconds) {
toolkit = Toolkit.getDefaultToolkit();
timer = new Timer();
timer.schedule(new RemindTask(), seconds * 1000);
}
class RemindTask extends TimerTask {
public void run() {
System.out.println("Time"s up!");
toolkit.beep();
//timer.cancel(); //Not necessary because we call System.exit
System.exit(0); //Stops the AWT thread (and everything else)
}
}
public static void main(String args[]) {
System.out.println("About to schedule task.");
new ReminderBeep(5);
System.out.println("Task scheduled.");
}
}
</source>
