I'm trying to implement a timer using one thread and print it on a JButton using another thread.
my class for time is like this:
public class Time extends Thread
{
int counter = 0;
public String currentTime = new String();
public String printFormat(int second)
{
return String.format("%d:%d", second/60, second%60);
}
synchronized public void count(int minute) throws InterruptedException
{
minute *= 60;
while(minute >= 0)
{
wait(1000);
minute--;
currentTime = printFormat(minute);
System.out.println(currentTime);
}
}
and my main thread is like this:
button.setText(time.currentTime);
what is wrong with this piece of code?
"if you can explain it using java swing timer , I would appreciate that"
If you want to use a javax.swing.Timer do the following, it really simple.
The same way you set a ActionListener to a button, you do the same for the timer. Except instead of the button firing the event, it's fired by the timer, every duration period you set for it.
In the case of a clock like timer, you would set it to 1000,
indication do something every 1000 milliseconds.
In this particular
example, I just set the text of the button with a count value that I
increment by one every time the timer event is fired. Heres the Timer code
Timer timer = new Timer(1000, new ActionListener(){
public void actionPerformed(ActionEvent e) {
button.setText(String.valueOf(count));
count++;
}
});
timer.start();
As you can see it' pretty simple
You can run this example
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class ButtonTimer {
private JButton button = new JButton(" ");
private int count = 1;
public ButtonTimer() {
Timer timer = new Timer(1000, new ActionListener(){
public void actionPerformed(ActionEvent e) {
button.setText(String.valueOf(count));
count++;
}
});
timer.start();
JFrame frame = new JFrame();
frame.add(button);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ButtonTimer();
}
});
}
}
If you want help trying to figure out your current code, consider posting a runnable program we can test out. So we can see where you're going wrong.
Here's a tutorial on Concurrency With Swing
Related
i am usin the timer class and in the docs it is written that i should import javax.swing.Timer to use it. does it mean that i can not use it in my normal java file? because i tried the below code, and it displays nothing:
static ActionListener timeStampListener = new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
System.out.println("action listener");
for (int i = 1; i <= logfile.getTotalLines(); i++) {
System.out.println("Engine Time(ms): " +
logfile.getFileHash().get(i).getTimeStampInSec());
}
}
};
Timer t = new Timer(2, timeStampListener);
t.setRepeats(true);
t.start();
the problem is your main thread exist before starting timer thread .since your application is non-gui use util.Timer instead Swing.Timer ..if you want to work this code using swing timer then add a swing component .add new jframe() and see it's working ..you don't need swing.timer use util timer .
static ActionListener timeStampListener1 = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("hi");
}
};
public static void main(String[] args) {
new JFrame(); //add this line
Timer t = new Timer(2, timeStampListener1);
t.setRepeats(true);
t.start();
}
or give some times by adding thread.sleep to timer to on and see it's working
Timer t = new Timer(2, timeStampListener1);
t.setRepeats(true);
t.start();
Thread.sleep(1000);
this is how can u use util timer for this
imports
import java.util.Timer;
import java.util.TimerTask;
code
public static void main(String[] args) {
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
System.out.println("action listener");
for (int i = 1; i <= logfile.getTotalLines(); i++) {
System.out.println("Engine Time(ms): "
+ logfile.getFileHash().get(i).getTimeStampInSec());
}
}
}, 500, 2);
}
No, it means that you should import which Timer class you will use. When you import javax.swing.Timer you specifies Timer class in javax.swing package. You can use it in your java file.
Anyway, have you tried not using static keyword with your timeStampListener?
I am trying to create a simple java program that will run indefinitely and output a number every second. I believe my code here should do this; however, it stops after the variable i gets to either 2, 3 or 4. Randomly. Most of the time it hits 3. I do not think that the program stopping is based on i at all, but something i'm overlooking perhaps.
All this program needs to do is spit out the second count using a timer. I feel like my code might be a little over complicated so please let me know if i'm making it too hard.
package testing;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class driver {
static int delay = 1000; //milliseconds
private Timer timer;
int i = 0;
public driver(){
ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println(i);
i++;
}
};
timer = new Timer(delay, taskPerformer);
timer.setInitialDelay(0);
timer.start();
}
public static void main(String args[]){
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
new driver();
}
});
}
}
Everything is just right in your program, but one.
Your program starts (from main() obviously), which starts the timer, timer method initiates the process of displaying time/number every second, and after that, the main thread dies! resulting in completion of program execution.
So to avoid this you simply can keep main thread busy.
Here's the simplest way :
public static void main(String args[]){
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
driver d = new driver();
}
});
for(;;); // <-- **Check this out :D**
}
I'm not sure how to even approach this but after doing some reading and a lot of attempts (failures) I've decided to ask the community for help. I have form A which opens and asks the user to enter a time to delay Form B from opening. Currently I am using sleep() to do this but now I would like to insert another dialog box to allow the user to interrupt the timer and bring up Form B before the timer runs out. I believe the correct way to do this is with wait() and notify() but I cannot seem to wrap my head around the numerous examples of producer and consumer models. Any help is appreciated.
A perfect job for javax.swing.Timer. Refer to How to Use Swing Timers for details. Here's an example to guide you in the right direction.
import java.awt.*;
import java.awt.event.*;
import javax.swing.Timer;
import javax.swing.*;
public class TimerDemo extends JFrame implements ActionListener {
private Timer timer;
private JButton jbDoSomethingDelayed;
private JButton jbDoItImmediately;
public TimerDemo() {
setLayout(new FlowLayout());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Timer demo");
jbDoSomethingDelayed = new JButton("Do something with a delay");
jbDoItImmediately = new JButton("Do it. Do it NOW!");
add(jbDoSomethingDelayed);
add(jbDoItImmediately);
jbDoItImmediately.setEnabled(false);
timer = new Timer(0, this); // we override delay later
timer.setRepeats(false); // we don't want it firing repeatedly
jbDoSomethingDelayed.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String msg = "Enter delay and confirm dialog";
JSpinner spinner = new JSpinner(new SpinnerNumberModel(5, 1, 10, 1));
Object[] content = new Object[] {msg, spinner};
int showConfirmDialog = JOptionPane.showConfirmDialog(TimerDemo.this, content, "Choose", JOptionPane.OK_CANCEL_OPTION);
if (showConfirmDialog == JOptionPane.OK_OPTION) {
// the important part
timer.setInitialDelay(((Integer)spinner.getValue()) * 1000);
jbDoSomethingDelayed.setEnabled(false);
jbDoItImmediately.setEnabled(true);
timer.start();
}
}
});
jbDoItImmediately.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.stop();
onTimerTimeout();
}
});
pack();
setLocationRelativeTo(null);
}
public void actionPerformed(ActionEvent e) {
// called by timer on EDT, no worries here
onTimerTimeout();
}
private void onTimerTimeout() {
jbDoSomethingDelayed.setEnabled(true);
jbDoItImmediately.setEnabled(false);
JOptionPane.showConfirmDialog(this, "You've done it now. No, really...", "It is done", JOptionPane.DEFAULT_OPTION, JOptionPane.INFORMATION_MESSAGE);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
TimerDemo demo = new TimerDemo();
demo.setVisible(true);
}
});
}
}
The simplest way would be in doing something like this
Thread a = new Thread(new Runnable(){
public void run(){
//do whatever display
try{
Thread.sleep(timeToShowBform);
}
catch(InterruptedException ex){
//interrupted.
}finally{
//show form B
SwingUtilities.invokeLater(...)
}
});
class BRunnable implements Runnable{
public void run(){
//if clicked, then this runnable is called.
a.interrupt();
}
}
The thread a suppose is blocked at sleep, then on calling a.interrupt() it wakes a.
I need a timer implemented in my application, which will do a countdown from 10 sec - 0 sec.
and, display the countdown in a JLabel.
Here's my implementation;
...
Timer t = new Timer(1000, new List());
t.start();
}
class List implements ActionListener{
#Override
public void actionPerformed(ActionEvent e) {
int sec = 0;
label.setText(""+sec);
// Do a if- condition check to see if the clock has reached to, and then stop
}
}
I was expecting the JLabel to start counting from 0 - 10 and then stop. But it doesn't. The JLabel set the value 0 and it doesn't get incremented.
UPDATE 1
t = new Timer(1000, new Listner());
t.start();
}
class Listner implements ActionListener{
private int counter = 0;
#Override
public void actionPerformed(ActionEvent e) {
lable.setText(""+ (counter++));
if (counter == 10)
t.removeActionListener(this);
}
}
You are not storing nor incrementing secs anywhere so I don't see how it should get updated, try with
Timer timer;
void start() {
timer = new Timer(1000,new List());
}
class List implements ActionListener {
private counter = 0;
#Override
public void actionPerformed(ActionEvent e) {
label.setText(""+counter++);
if (counter == 10)
timer.removeActionListener(this);
}
}
Mind that you need to store a reference to the timer somewhere to be able to remove the listener from it once countdown finished.
Well each time the timer is called it declares the int variable sec to 0. Hence the Label doesnt get updated.
You should declare the sec variable as a global variable and then in the actionPerformed method increment its value each time it is called.
public int sec = 0;
class List implements ActionListener{
#Override
public void actionPerformed(ActionEvent e) {
sec++;
label.setText(""+sec);
// Do a if- condition check to see if the clock has reached to, and then stop
}
}
A complete example
public class ATimerExample {
Timer timer;
int counter = 0;
public ATimerExample() {
final JFrame frame = new JFrame("somethgi");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JLabel label = new JLabel("0");
JPanel panel = new JPanel();
panel.add(label, BorderLayout.SOUTH);
frame.getContentPane().add(panel);
frame.pack();
frame.setVisible(true);
timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
label.setText(String.valueOf(counter));
counter++;
if (counter == 10) {
//timer.removeActionListener(this);
timer.stop();
}
}
});
timer.start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new ATimerExample();
}
});
}
}
Since java reads the time in milliseconds, it should be 10000 instead of 1000. try your code and see if that works. I had the same problem when I wanted 30 seconds. And instead of writing Timer t = new Timer(30000, new List()); t.start();
I wrote Timer t = new Timer(3000, new List());
t.start();
That made my program to stop every after 3 seconds. I would suggest, you use 10000 instead of 1000.
Remember to do: t.stop() in your List class. Thanks
Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer?
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public class CountdownNew {
static JLabel label;
// Method which defines the appearance of the window.
public static void showGUI() {
JFrame frame = new JFrame("Simple Countdown");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
label = new JLabel("Some Text");
frame.add(label);
frame.pack();
frame.setVisible(true);
}
// Define a new thread in which the countdown is counting down.
public static Thread counter = new Thread() {
public void run() {
for (int i=10; i>0; i=i-1) {
updateGUI(i,label);
try {Thread.sleep(1000);} catch(InterruptedException e) {};
}
}
};
// A method which updates GUI (sets a new value of JLabel).
private static void updateGUI(final int i, final JLabel label) {
SwingUtilities.invokeLater(
new Runnable() {
public void run() {
label.setText("You have " + i + " seconds.");
}
}
);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
showGUI();
counter.start();
}
});
}
}
Yes you SHOULD use a Swing Timer. You SHOULD NOT, use a util Timer and TimerTask.
When a Swing Timer fires the code is executed on the EDT which means you just need to invoke the label.setText() method.
When using the uitl Timer and TimerTask, the code DOES NOT execute on the EDT, which means you need to wrap your code in a SwingUtilities.invokeLater to make sure the code executes on the EDT.
And that is way using a Swing Timer is shorter and more elegant than your current approach, it simplifies the coding because to code is executed on the EDT.
You could make it a little more elegant by using Timer with an appropriate TimerTask.
Yes, use a timer. updateGUI would be the code for the timer task, but it will need some changes as you won't be able to pass in i for each call since you just get a run() method.