We Keep Coding

How to make a pause-able count up timer in Java?

I'm trying to make a timer that will count up from 00h:00m:00s, with the ability to pause and restart the count from its current time.
Heres the solution I currently have: It will always restart the timer from 0 instead of continuing where it left off. Also, for another inexplicable reason, the hours always display as 07 instead of 00. Does anyone know how I could fix these issues, to have it start counting up from its previous value, and display the correct amount of hours elapsed?
private final SimpleDateFormat date = new SimpleDateFormat("KK:mm:ss");
private long startTime = 0;
private final ClockListener clock = new ClockListener();
private final Timer normalTimer = new Timer(53, clock);
startTimerButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(startTime == 0) {
startTime = System.currentTimeMillis();
}
else {
startTime += (System.currentTimeMillis() - startTime);
}
normalTimer.start();
}
});
stopTimerButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
normalTimer.stop();
}
});
private void updateClock(){
Date elapsed = new Date(System.currentTimeMillis() - startTime);
timerText.setText(date.format(elapsed));
}
private class ClockListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
updateClock();
}
}

Introduction
Oracle has a helpful tutorial, Creating a GUI With Swing. Skip the Learning Swing with the NetBeans IDE section.
Your code wasn't runnable, so I created the following GUI.
When you press the "Start" button, the timer starts counting. 37 seconds.
2 minutes, 7 seconds.
1 hour, 6 minutes, 11 seconds.
Pressing the "Pause button pauses the count. Pressing the "Restart" button resumes the count. You can pause and resume the count as many times as you want.
Pressing the "Stop" button stops the counter. You can press the "Reset" button to reset the counter before starting again.
Explanation
When creating a Swing application, using the model-view-controller (MVC) pattern helps to separate your concerns and allows you to focus on one part of the application at a time.
Creating the application model made creating the GUI much easier. The application model is made up of one or more plain Java getter/setter classes.
The CountupTimerModel class keeps long fields to hold the duration in milliseconds and the previous duration. This way, I don't have to pause and restart the Swing Timer.
The duration is the difference between the current time and the start time. I use the System.currentTimeMillis() method to calculate the duration.
The GUI is fairly straightforward.
I made the JButton ActionListeners lambdas. I made the TimerListener a separate class to move the code out of that particular lambda.
Code
Here's the complete runnable code. I made the additional classes inner classes so I could post the code as one block.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class CountupTimerGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new CountupTimerGUI());
}
private final CountupTimerModel model;
private JButton resetButton, pauseButton, stopButton;
private JLabel timerLabel;
public CountupTimerGUI() {
this.model = new CountupTimerModel();
}
#Override
public void run() {
JFrame frame = new JFrame("Countup Timer GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createDisplayPanel(), BorderLayout.NORTH);
frame.add(createButtonPanel(), BorderLayout.SOUTH);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createDisplayPanel() {
JPanel panel = new JPanel(new FlowLayout());
panel.setBorder(BorderFactory.createEmptyBorder(0, 5, 5, 5));
Font font = panel.getFont().deriveFont(Font.BOLD, 48f);
timerLabel = new JLabel(model.getFormattedDuration());
timerLabel.setFont(font);
panel.add(timerLabel);
return panel;
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel(new FlowLayout());
panel.setBorder(BorderFactory.createEmptyBorder(0, 5, 5, 5));
Font font = panel.getFont().deriveFont(Font.PLAIN, 16f);
resetButton = new JButton("Reset");
resetButton.setFont(font);
panel.add(resetButton);
resetButton.addActionListener(event -> {
model.resetDuration();
timerLabel.setText(model.getFormattedDuration());
});
pauseButton = new JButton("Restart");
pauseButton.setFont(font);
panel.add(pauseButton);
pauseButton.addActionListener(event -> {
String text = pauseButton.getText();
if (text.equals("Pause")) {
model.pauseTimer();
pauseButton.setText("Restart");
} else {
model.startTimer();
pauseButton.setText("Pause");
}
});
Timer timer = new Timer(200,
new CountupListener(CountupTimerGUI.this, model));
stopButton = new JButton("Start");
stopButton.setFont(font);
panel.add(stopButton);
stopButton.addActionListener(event -> {
String text = stopButton.getText();
if (text.equals("Start")) {
model.resetDuration();
model.startTimer();
timer.start();
resetButton.setEnabled(false);
stopButton.setText("Stop");
} else {
model.stopTimer();
timer.stop();
resetButton.setEnabled(true);
stopButton.setText("Start");
}
});
Dimension d = getLargestJButton(resetButton, pauseButton, stopButton);
resetButton.setPreferredSize(d);
pauseButton.setPreferredSize(d);
stopButton.setPreferredSize(d);
pauseButton.setText("Pause");
return panel;
}
private Dimension getLargestJButton(JButton... buttons) {
Dimension largestDimension = new Dimension(0, 0);
for (JButton button : buttons) {
Dimension d = button.getPreferredSize();
largestDimension.width = Math.max(largestDimension.width, d.width);
largestDimension.height = Math.max(largestDimension.height,
d.height);
}
largestDimension.width += 10;
return largestDimension;
}
public JButton getResetButton() {
return resetButton;
}
public JButton getPauseButton() {
return pauseButton;
}
public JButton getStopButton() {
return stopButton;
}
public JLabel getTimerLabel() {
return timerLabel;
}
public class CountupListener implements ActionListener {
private final CountupTimerGUI view;
private final CountupTimerModel model;
public CountupListener(CountupTimerGUI view, CountupTimerModel model) {
this.view = view;
this.model = model;
}
#Override
public void actionPerformed(ActionEvent event) {
model.setDuration();
view.getTimerLabel().setText(model.getFormattedDuration());
}
}
public class CountupTimerModel {
private boolean isRunning;
private long duration, previousDuration, startTime;
public CountupTimerModel() {
resetDuration();
}
public void resetDuration() {
this.duration = 0L;
this.previousDuration = 0L;
this.isRunning = true;
}
public void startTimer() {
this.startTime = System.currentTimeMillis();
this.isRunning = true;
}
public void pauseTimer() {
setDuration();
this.previousDuration = duration;
this.isRunning = false;
}
public void stopTimer() {
setDuration();
this.isRunning = false;
}
public void setDuration() {
if (isRunning) {
this.duration = System.currentTimeMillis() - startTime
+ previousDuration;
}
}
public String getFormattedDuration() {
int seconds = (int) ((duration + 500L) / 1000L);
int minutes = seconds / 60;
int hours = minutes / 60;
StringBuilder builder = new StringBuilder();
if (hours > 0) {
builder.append(hours);
builder.append(":");
}
minutes %= 60;
if (hours > 0) {
builder.append(String.format("%02d", minutes));
builder.append(":");
} else if (minutes > 0) {
builder.append(minutes);
builder.append(":");
}
seconds %= 60;
if (hours > 0 || minutes > 0) {
builder.append(String.format("%02d", seconds));
} else {
builder.append(seconds);
}
return builder.toString();
}
}
}

Why is my looping GUI timer not showing up?

I'm trying to make a GUI timer without using javax.swing.Timer(kind of a strange task), but I am having trouble making it work. It's supposed to sleep the thread for 1 second, add 1 to seconds, and repeat(infinitely). When I run my program, the icon shows up, but the window does not appear. I'm guessing my error is in the Thread.sleep(1000); line or in that area, but I'm not sure why it doesn't work. Is Thread.sleep(millis)not compatible with swing applications? Do I have to multithread? Here's my program:
import java.awt.*;
import javax.swing.*;
public class GUITimer extends JFrame {
private static final long serialVersionUID = 1L;
private int seconds = 0;
public GUITimer() {
initGUI();
pack();
setVisible(true);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
private void initGUI(){
JLabel title = new JLabel("Timer");
Font titleFont = new Font(Font.SERIF, Font.BOLD, 32);
title.setFont(titleFont);
title.setHorizontalAlignment(JLabel.CENTER);
title.setBackground(Color.BLACK);
title.setForeground(Color.WHITE);
title.setOpaque(true);
add(title, BorderLayout.NORTH);
JLabel timeDisplay = new JLabel(Integer.toString(seconds));//this label shows seconds
add(timeDisplay, BorderLayout.CENTER);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
seconds++;
initGUI();
}
public static void main(String[] args) {
try {
String className = UIManager.getCrossPlatformLookAndFeelClassName();
UIManager.setLookAndFeel(className);
}
catch (Exception e) {}
EventQueue.invokeLater(new Runnable() {
public void run() {
new GUITimer();
}
});
}
}
EDIT:
I noticed when I print seconds in my method initGUI() to console, it prints them incrementally by one second correctly. So when it looks like:
private void initGUI() {
System.out.println(seconds);
//...
it prints the value of seconds after every second(How the JLabel should). This shows that my loop is working fine, and my Thread.sleep(1000) is OK also. My only problem now, is that the frame is not showing up.

Your main window does not appear, because you called infinite recursion inside constructor. GUITimer will not be created and this lock main thread.
You need use multithreading for this aim. Main thread for drawing time, second thread increment and put value to label
For example:
import javax.swing.*;
import java.awt.*;
public class GUITimer extends JFrame
{
private static final long serialVersionUID = 1L;
private int seconds = 0;
private Thread timerThread;
private JLabel timeDisplay;
public GUITimer()
{
initGUI();
pack();
setVisible(true);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
private void initGUI()
{
JLabel title = new JLabel("Timer");
Font titleFont = new Font(Font.SERIF, Font.BOLD, 32);
title.setFont(titleFont);
title.setHorizontalAlignment(JLabel.CENTER);
title.setBackground(Color.BLACK);
title.setForeground(Color.WHITE);
title.setOpaque(true);
add(title, BorderLayout.NORTH);
timeDisplay = new JLabel(Integer.toString(seconds));//this label shows seconds
add(timeDisplay, BorderLayout.CENTER);
}
public void start()
{
seconds = 0;
timerThread = new Thread(new Runnable()
{
#Override
public void run()
{
while(true)
{
timeDisplay.setText(Integer.toString(seconds++));
try
{
Thread.sleep(1000L);
}
catch(InterruptedException e) {}
}
}
});
timerThread.start();
}
public void stop()
{
timerThread.interrupt();
}
public static void main(String[] args)
{
try
{
GUITimer timer = new GUITimer();
timer.start();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}

The core issue is, you're blocking the UI by continuously calling initGUI, which will eventually fail with a StackOverFlowException, as the method calls never end
The preference would be to use a Swing Timer, but since you've stated you don't want to do that, a better solution would be to use a SwingWorker, the reason for this - Swing is NOT thread safe and SwingWorker provides a convenient mechanism for allowing us to update the UI safely.
Because both Swing Timer and Thead.sleep only guarantee a minimum delay, they are not a reliable means for measuring the passage of time, it would be better to make use of Java 8's Date/Time API instead
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel label = new JLabel("00:00:00");
private TimeWorker timeWorker;
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(label, gbc);
JButton button = new JButton("Start");
add(button, gbc);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (timeWorker == null) {
timeWorker = new TimeWorker(label);
timeWorker.execute();
button.setText("Stop");
} else {
timeWorker.cancel(true);
timeWorker = null;
button.setText("Start");
}
}
});
}
}
public class TimeWorker extends SwingWorker<Void, Duration> {
private JLabel label;
public TimeWorker(JLabel label) {
this.label = label;
}
#Override
protected Void doInBackground() throws Exception {
LocalDateTime startTime = LocalDateTime.now();
Duration totalDuration = Duration.ZERO;
while (!isCancelled()) {
LocalDateTime now = LocalDateTime.now();
Duration tickDuration = Duration.between(startTime, now);
publish(tickDuration);
Thread.sleep(500);
}
return null;
}
#Override
protected void process(List<Duration> chunks) {
Duration duration = chunks.get(chunks.size() - 1);
String text = format(duration);
label.setText(text);
}
public String format(Duration duration) {
long hours = duration.toHours();
duration = duration.minusHours(hours);
long minutes = duration.toMinutes();
duration = duration.minusMinutes(minutes);
long millis = duration.toMillis();
long seconds = (long)(millis / 1000.0);
return String.format("%02d:%02d:%02d", hours, minutes, seconds);
}
}
}

Why is my thread not working properly in Swing?

I am printing simple value to append JTextArea using simple for loop, and when I run it, it's properly Run if I print value in console output...
But if I append JTextArea and print value in the text area, they are appended all after whole program run.
public class SwingThread {
private JFrame frame;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SwingThread window = new SwingThread();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public SwingThread() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
JTextArea textArea = new JTextArea();
scrollPane.setViewportView(textArea);
JButton btnNewButton = new JButton("New button");
scrollPane.setColumnHeaderView(btnNewButton);
btnNewButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent arg0)
{
try
{
for(int i = 0 ; i <= 5 ; i++)
{
textArea.append("Value "+i+"\n");
System.out.println("Value is" + i);
Thread.sleep(1000);
}
}
catch(Exception e)
{
System.out.println("Error : "+e);
}
}
});
}
}
I want to append one by one, but it was appended after the whole program runs.

Your problem is with your use of Thread.sleep, since when you call this on the Swing event thread (or EDT for Event Dispatch Thread) as you are doing, it will put the entire Swing event thread to sleep. When this happens the actions of this thread cannot be performed, including painting the GUI (updating it) and interacting with the user, and this will completely freeze your GUI -- not good. The solution in this current situation is to use a Swing Timer as a pseudo-loop. The Timer creates a loop within a background thread and guarantees that all code within its actionPerformed method will be called on the Swing event thread, a necessity here since we don't want to append to the JTextArea off of this thread.
Also as others have noted, if all you want to do is to perform a repeated action with delay in Swing, then yes, use this Swing Timer. If on the other hand you wish to run a long-running bit of code in Swing, then again this code will block the EDT and will freeze your program. For this situation use a background thread such as one supplied by a SwingWorker. Please check out Lesson: Concurrency in Swing for more on this.
e.g.,
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
// delay between timer ticks: 1000
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener() {
private int counter = 0;
#Override
public void actionPerformed(ActionEvent e) {
// timer's stopping condition
if (counter >= MAX_VALUE) { // MAX_VALUE is a constant int = 5
((Timer) e.getSource()).stop();
} else {
textArea.append("Value " + counter + "\n");
}
counter++; // increment timer's counter variable
}
}).start();
}
});
The whole thing:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.*;
import javax.swing.*;
public class SwingThread2 {
protected static final int MAX_VALUE = 5; // our constant
private JFrame frame;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SwingThread2 window = new SwingThread2();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public SwingThread2() {
initialize();
}
private void initialize() {
frame = new JFrame();
// frame.setBounds(100, 100, 450, 300); // avoid this
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
JTextArea textArea = new JTextArea(15, 40);
scrollPane.setViewportView(textArea);
JButton btnNewButton = new JButton("New button");
scrollPane.setColumnHeaderView(btnNewButton);
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
// delay between timer ticks: 1000
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener() {
private int counter = 0;
#Override
public void actionPerformed(ActionEvent e) {
// timer's stopping condition
if (counter >= MAX_VALUE) { // MAX_VALUE is a constant int = 5
((Timer) e.getSource()).stop();
} else {
textArea.append("Value " + counter + "\n");
}
counter++; // increment timer's counter variable
}
}).start();
}
});
// better to avoid setting sizes but instead to
// let the components size themselves vis pack
frame.pack();
frame.setLocationRelativeTo(null);
}
}
Just for further information, here is an example of the same program above that uses a SwingWorker to perform a long running action, and then update a JProgressBar with this action. The worker is quite simple, and simply uses a while loop to advance a counter variable by a bounded random amount. It then transmits uses this value to update its own progress property (a value that can only be from 0 to 100, and so in other situations, the value will need to be normalized to comply with this). I attach a PropertyChangeListener to the worker, and this is notified on the Swing event thread whenever the worker's progress value changes and also whenever the SwingWorker changes state, such as when it is done operating. In the latter situation, the worker's StateValue becomes StateValue.DONE. The listener then updates the GUI accordingly. Please ask if any questions.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
public class SwingThread2 {
protected static final int MAX_VALUE = 5; // our constant
private JFrame frame;
private JProgressBar progressBar = new JProgressBar();
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
SwingThread2 window = new SwingThread2();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public SwingThread2() {
initialize();
}
private void initialize() {
frame = new JFrame();
// frame.setBounds(100, 100, 450, 300); // avoid this
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
JTextArea textArea = new JTextArea(15, 40);
scrollPane.setViewportView(textArea);
JButton btnNewButton = new JButton("New button");
scrollPane.setColumnHeaderView(btnNewButton);
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
// delay between timer ticks: 1000
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener() {
private int counter = 0;
#Override
public void actionPerformed(ActionEvent e) {
// timer's stopping condition
if (counter >= MAX_VALUE) { // MAX_VALUE is a constant
// int = 5
((Timer) e.getSource()).stop();
} else {
textArea.append("Value " + counter + "\n");
}
counter++; // increment timer's counter variable
}
}).start();
}
});
progressBar.setStringPainted(true);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.LINE_AXIS));
bottomPanel.add(new JButton(new MyAction("Press Me")));
bottomPanel.add(progressBar);
frame.getContentPane().add(bottomPanel, BorderLayout.PAGE_END);
// better to avoid setting sizes but instead to
// let the components size themselves vis pack
frame.pack();
frame.setLocationRelativeTo(null);
}
private class MyAction extends AbstractAction {
public MyAction(String name) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
public void actionPerformed(ActionEvent e) {
progressBar.setValue(0);
setEnabled(false);
MyWorker myWorker = new MyWorker();
myWorker.addPropertyChangeListener(new WorkerListener(this));
myWorker.execute();
}
}
private class WorkerListener implements PropertyChangeListener {
private Action action;
public WorkerListener(Action myAction) {
this.action = myAction;
}
#Override
public void propertyChange(PropertyChangeEvent evt) {
if ("progress".equals(evt.getPropertyName())) {
int progress = (int) evt.getNewValue();
progressBar.setValue(progress);
} else if ("state".equals(evt.getPropertyName())) {
if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
action.setEnabled(true);
#SuppressWarnings("rawtypes")
SwingWorker worker = (SwingWorker) evt.getSource();
try {
// always want to call get to trap and act on
// any exceptions that the worker might cause
// do this even though get returns nothing
worker.get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
}
}
}
private class MyWorker extends SwingWorker<Void, Void> {
private static final int MULTIPLIER = 80;
private int counter = 0;
private Random random = new Random();
#Override
protected Void doInBackground() throws Exception {
while (counter < 100) {
int increment = random.nextInt(10);
Thread.sleep(increment * MULTIPLIER);
counter += increment;
counter = Math.min(counter, 100);
setProgress(counter);
}
return null;
}
}
}

Require assistance on stopping a timer when a slider change has occured

I'm trying to create a animation by importing pictures from a sprite sheet and changing the speed using a timer. When I set the speed for the first time, it works perfectly, but anytime after that it wont change the speed. The previous speed will continue playing and I get this error in the output: http://imgur.com/a/sWhmQ
Any help would be appreciated.
Here is what I have so far:
Edit: Found the problem for the timerTask & moved it into the ChangeListener, however, the speed still does not change when the slider moves.
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.util.Timer;
import java.util.TimerTask;
public class AnimationGUI {
private static int counter = 0;
private static JLabel value = new JLabel("0");
private static JLabel image = new JLabel("");
private static Timer timer = new Timer();
public static void main(String[] args) {
JFrame frame = new JFrame("Animation GUI");
JPanel panel = new JPanel();
JSlider slider = new JSlider(JSlider.HORIZONTAL, 1, 10, 1);
slider.addChangeListener(new Slider());
frame.setVisible(true);
frame.setSize(500, 500);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(panel);
panel.add(slider);
panel.add(value);
panel.add(image);
}
private static class Slider implements ChangeListener {
public void stateChanged(ChangeEvent event) {
JSlider source = (JSlider) event.getSource();
TimerTask task = new TimerTask() {
public void run() {
image.setIcon(new ImageIcon(counter + ".png"));
counter++;
if (counter > 12) {
counter = 0;
}
}
};
if (!source.getValueIsAdjusting()) {
value.setText("" + (int) source.getValue());
int speed = source.getValue() * 100;
timer.scheduleAtFixedRate(task, 0, speed);
}
}
}
}

First recommendation, use a Swing Timer instead of a TimerTask, apart from been self contained and supporting things like stop, start and restart, it's also safe to use for updating the UI from - Swing is not thread safe
Something like...
private static class Slider implements ChangeListener {
private Timer timer;
public Slider() {
timer = new Timer(16, new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
image.setIcon(new ImageIcon(counter + ".png"));
counter++;
if (counter > 12) {
counter = 0;
}
}
});
timer.start()
}
public void stateChanged(ChangeEvent event) {
JSlider source = (JSlider) event.getSource();
if (!source.getValueIsAdjusting()) {
value.setText("" + (int) source.getValue());
int speed = source.getValue() * 100;
timer.setDelay(speed);
}
}
}
as an example
See How to use Timers for more details

I suspect that you need to cancel the existing TimerTask and start a new one with the desired speed.

How to put timer into a GUI?

I have a GUI with a form for people to fill up and I would like to put a countdown timer at the top right hand corner of the page
Heres the method for the timer to get the remaining time. Say my form class is FillForm and the timer method is found in Timer.
How do I put a dynamic (constantly updating) timer inside of the GUI?
public String getRemainingTime() {
int hours = (int)((this.remainingTime/3600000) % 60);
int minutes = (int)((this.remainingTime/60000) % 60);
int seconds = (int)(((this.remainingTime)/1000) % 60);
return(format.format(hours) + ":" + format.format(minutes)+
":" + format.format(seconds));
}
GUI is built using NetBeans GUI builder.

Try This :
import javax.swing.Timer;
Timer timer=new Timer(1000,new ActionListener(){
public void actionPerformed(ActionEvent e)
{
//code here
}
});
timer.start();
//timer.stop()
Every one Seconds Timer Execute.
Try This Demo :
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.Timer;
class Counter {
private static int cnt;
static JFrame f;
public static void main(String args[]) {
f=new JFrame();
f.setSize(100,100);
f.setVisible(true);
ActionListener actListner = new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
cnt += 1;
if(cnt%2==0)
{
f.setVisible(true);
}
else
{
f.setVisible(false);
}
}
};
Timer timer = new Timer(500, actListner);
timer.start();
}
}

You should abstract your timer into a UI component. JLabel seems the most suited as it is a text that you want to display.
public class TimerLabel extends JLabel {
// Add in your code for 'format' and 'remainingTime'.
// Note that the first time that 'getText' is called, it's called from the constructor
// if the superclass, so your own class is not fully initialized at this point.
// Hence the 'if (format != null)' check
public TimerLabel() {
Timer timer = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent e) {
repaint();
}
});
timer.start();
}
public String getRemainingTime() {
int hours = (int) ((this.remainingTime / 3600000) % 60);
int minutes = (int) ((this.remainingTime / 60000) % 60);
int seconds = (int) (((this.remainingTime) / 1000) % 60);
return (format.format(hours) + ":" + format.format(minutes) + ":" + format.format(seconds));
}
#Override
public String getText() {
if (format != null) {
return getRemainingTime();
} else {
return "";
}
}

"Could i add this into a Swing.JPanel or something?"
Just put it in the constructor of your form class. Declare the Timer timer; as a class member and not locally scoped so that you can use the start() method like in a button's actionPerformed. Something like
import javax.swing.Timer;
public class GUI extends JFrame {
public Timer timer = null;
public GUI() {
timer = new Timer (500, new ActionListener(){
public void actionPerformed(ActionEvent e) {
if (timerGetsToZero) {
((Timer)e.getSource()).stop();
} else {
timeLabel.setText(getRemainingTime());
}
}
});
}
private void startButtonActionPerformed(ActionEvent e) {
timer.start();
}
}