Develop Reference

How to pause and resume a Java application that writes on a text file

I have a little program which writes the current date and the current time into a text file. However, it continues write until I close the frame. So I added a pause button to it and wish to pause and resume the program instead of have to close and start it again (if is that makes sense).
So is there anyway that I can achieve this?
Many thanks in advance!!!
please see the code below
class RecordTask extends TimerTask {
public void run() {
try {
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("breaths.txt", true)));
out.println(new Date().toString());
out.close();
Breaths++;
lblB.setText("Breaths: " + Breaths);
} catch (IOException e) {
JOptionPane.showMessageDialog(new JFrame(), e.toString(), "",
JOptionPane.ERROR_MESSAGE);
}
}
}
public void actionPerformed(ActionEvent event) {
// Check if Start button is pressed
if (event.getSource() == startButton) {
int value = (int) txtRate.getValue();
timer = new Timer();
int interval = (int)((((double) 60) / (double) value) * 1000);
timer.scheduleAtFixedRate(new RecordTask(), interval, interval);
startButton.setEnabled(false);
} else // Check if pause button pressed
if (event.getSource() == pauseButton) {
//Pause the breaths
} else // Check if exit button pressed
if (event.getSource() == exitButton) {
// close the program
System.exit(0);
}
}
So I basically need to pause the function and resume it. :)

Instead of java.util.Timer use javax.swing.Timer. It has methods start(), stop(). Moreover, java.util.Timer is not safe regarding Swing API because schedules tasks in a thread other than EDT and you use in your task JOptionPane.showMessageDialog.

Thread.sleep() to swing Timer conversion

I am trying to implement a Thread.sleep(6000) line but it seems to freeze in the applet. When I tried to use Timers, I wasn't sure how to use because I am not very good with event listeners. I am basically trying to call a method fetchUrl() every 6 seconds, after the user clicks the enter button. How can I implement this?
public void init() {
c = getContentPane();
c.setLayout(flow);
c.setBackground(forum);
question.setForeground(Color.white);
question.setFont(tnr);
question2.setForeground(Color.white);
question2.setFont(tnr);
result.setForeground(Color.white);
result.setFont(tnr);
resp.setBorder(BorderFactory.createBevelBorder(0));
timeLength.setBorder(BorderFactory.createBevelBorder(0));
c.add(question);
c.add(resp);
c.add(question2);
c.add(timeLength);
c.add(enter);
c.add(result);
resp.requestFocus();
enter.addActionListener(this);
t = new Timer(DELAY, this);
t.setInitialDelay(DELAY);
}
public void actionPerformed(ActionEvent e) {
final String n1;
int timeMin, timeSec, count = 0, maxCount;
timeMin = Integer.parseInt(timeLength.getText());
timeSec = timeMin * 60;
maxCount = (int)(timeSec/6);
if (e.getSource() == enter) { //user clicks enter
n1 = resp.getText();
while (count < maxCount) {
fetchUrl(n1); //this method called every 6 seconds
t.start();
count++;
}
}
}

First I would start by separating the ActionListener for the Timer and for the JButton.
Second nothing is happening logically with the Timer because you're swallowing it with the button source check.
Third you should understand how the timer works. Basically for every "tick" (in your case six seconds) the actionPerformed of the timer ActionListener is called. So if you want the fetch() method called, then that's what you should be visible/accessible to the in the Timer's actionPerformed.
The button's ActionListener should only handle the starting of the timer I believe. So just separate the listeners. Give each one an anonymous ActionListener and no need to make the class implement ActionListener.
For example
timer = new Timer(DELAY, new ActionListener(){
public void actionPerformed(ActionEvent e) {
// do some stuff every six seconds
fetchURL();
}
});
enter = new JButton(...);
enter.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
If you want some automatic stopping feature for the timer, you could do something like
timer = new Timer(DELAY, new ActionListener(){
public void actionPerformed(ActionEvent e) {
if (someStoppingCondition()) {
timer.stop();
} else {
// do some stuff every six seconds
fetchURL();
}
// do some stuff every six second
}
});

You need to call a method after user clicks on button every 6 seconds, but you have not said how many times you want to call it.
For infinite number of times, try something like the following,
while(true){
new Thread(){
#Override
public void run(){
try{
Thread.sleep(6000);
fetchUrl(n1);
}catch(InterruptedException e){}
}
}.start();
}
If you will use Thread.sleep() in your applet, then your applet will be hanged for 6 seconds and so create a new thread for it.

How to display a Swing timer's remaining time in one second intervals?

I've been working on a simple game using a Java Applet in which the player's goal is to get as many points as possible within a 30 second timeframe. Right now, I'm using a Swing timer to count down from 30 seconds, and once the 0 mark is reached, a "game over" screen is displayed with the player's score. I have these instance variables:
ActionListener listener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
screenState = 0;
repaint();
}
};
Timer displayTimer = new Timer(30000, listener);
When the player clicks the "play" button, I execute displayTimer.start();.
Then, I have this within the appropriate case in my paint class:
g.drawString("Time Remaining: " + displayTimer.getDelay()/1000, 650, 100);
So, obviously, right now it's just displaying a static "Time Remaining: 30", and the screens switches after 30 seconds. What I'm trying to figure out is how I can repaint this value every one second so that it's a live timer. The only help I've been able to find thus far is for people use components.

ActionListener listener = new ActionListener() {
int count = 0;
#Override
public void actionPerformed(ActionEvent e) {
if (count++==30) {
screenState = 0;
}
repaint();
}
};
Timer displayTimer = new Timer(1000, listener); // make it 30 times faster

You can use the a Thread that sleep it every one second using the sleep method of it
Here is a little sample that count to 30 with 1 second interval
public static void main(String[] args) {
Thread t = new Thread(new Runnable() {
#Override
public void run() {
int count = 0;
while(true)
{
if(count == 30) //end at 30 second
break;
try {
Thread.sleep(1000);
System.out.println("updated");
++count;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
});
t.start();
}

How do you convert thread.sleep to javax.swing.timer?

Is there a way to easily convert thread.sleep to javax.swing.timer?
The reason why I would need to do this, is to stop the user-interface from freezing when you press a button, so that you can implement a pause button.
Code Example:
btnStartTiming.addMouseListener(new MouseAdapter() {
#Override
public void mouseReleased(MouseEvent arg0) {
try{
inputA = Double.parseDouble(txtEnterHowLong.getText()); //Changes double to string and receives input from user
}catch(NumberFormatException ex){
}
while (counter <= inputA){
txtCounter.setText(counter + "");
try {
Thread.sleep(1000);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
System.out.println(counter);
counter++;
}
}
});

Some tips:
Take a look to How to use Swing
Timers
trail and come back with concrete problems. Describe what are you trying to accomplish and your work so far, show your attempts to solve the problem and make an answerable question.
Don't use MouseListener
to listen when a button is pressed. Use ActionListener
instead. Take a look to How to Use Buttons, Check Boxes, and Radio
Buttons trail.

Put the java.swing.Timer in your constructor. You can use the button to .start() the timer.
Also instead of the while, you can add an if statement in the timer code check when to .stop()
Something like this
int delay = 1000;
Timer timer = new Timer(delay, null);
public Constructor(){
timer = new Timer(delay, new ActionListener(){
public void actionPerformed(ActionEvent e) {
if (counter >= inputA) {
timer.stop();
} else {
// do something
}
}
});
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
}

How to stop the timer function after the object has been shot?

I am making a simple target shooting game.I have a countdownTimer inside the label and an object that blinks in a random position inside the panel. Every time I click on the object,. the object's timer stops which makes that object stop too, but the countdown timer doesn't and that is my problem. I want the countdown timer should stop also.
Could someone help me about this matter?
Here's the code :
private void starting()
{
new Timer(TIMER_PERIOD, new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
if (count++ < MAX_COUNT)
{
String text = "Time remaining: (" + (MAX_COUNT - count) + ") seconds left";
setCountDownLabelText(text);
Date date = new Date();
setCountDownPanelText(date);
}
else
{
((Timer) e.getSource()).stop();
randomTimer.stop();
JOptionPane.showMessageDialog(null, "Game Over");
System.exit(0);
}
}
}).start();
}

It strikes me that you don't understand the code at all, that you are unaware of the anonymous class created that is extending Timer, which (if you'd seen the documentation) has a function stop() which does what you ask.
You need to store a reference to the Timer.
private javax.swing.Timer timer;
private void starting() {
timer = new Timer(TIMER_PERIOD, new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
// do stuff
// stop the timer
timer.stop();
// do other stuff
}
}
}