Develop Reference

Restarting Java timer with a different time interval

I'm working on creating a timer in Java, and was wondering how I can use timer.cancel to then create a new timer which has a different interval.
My code looks something like this:
final Timer timer = new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() {
handler.post(new Runnable() {
#Override
public void run() {
gameView.invalidate();
// timer.cancel(); - here, need to somehow restart timer with new interval
}
});
}
}, 0, TimerInterval.interval);
In another view, I'm modifying TimerInterval.interval, but this doesn't do anything/update the timer, because I need to somehow completely cancel the timer and create a new one, but I'm not sure how to do this.
Any help with this matter would be appreciated.

How to force a timer to start immediately

I am using a timer that should every 12 seconds issues a warning. as shown in the code below i set the delay to 0 so that the timer starts immediately, but at
run time, the below posted timer does not starts immediately it waits for the period set as a delay despit i set the delay to 0
in other words, the below timer should wait 0 sec as a delay and repeats itself every 12 seconds but what happens is, it at initial execution it waits 12 sec and repeat itself every 12 sec
any logical explaination why that is happening
code:
mVelWarningRule1Timer.scheduleAtFixedRate(
new SpeakOut(
getApplicationContext(),
getApplicationContext()
.getResources()
.getString(R.string.rule_velocity_1)),
0,
getApplicationContext()
.getResources()
.getInteger(R.integer.int_assistWarning_interval)
);

Timer timer = new Timer();
timer.scheduleAtFixedRate(new RemindTask(), 0, 12000);
The first is the internal class. The second parameter is the delay. The third gives you the interval.
private class RemindTask extends TimerTask {
#Override
public void run() {
try
{
getActivity().runOnUiThread(new Runnable() {
public void run() {
if (page > adapter.getCount()) {
page = 0;
} else {
viewPager.setCurrentItem(page++, true);
}
}
});
}
catch(Exception e)
{
timer.cancel();
}
}
}
This would make a carousel of pictures change every 12 seconds

How to work with Swing timer

I'm trying to stop the program for a second using Swing Timer.
Timer timer = new Timer(10000,
new ActionListener(public void actionPerformed(ActionEvent e) {}));
didn't work
public class Card extends JButton implements ActionListener {
int numberClick = 0;
public card() {
addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
numberClick++;
if(numberClick == 2) {
Timer timer = new Timer(10000, );
timer.start();
numberClick = 0;
}
}
}

You seem to lack basic understanding of how the Timer works. Please read How to Use Swing Timers. The concept is fairly simple.
The first argument in the Timer constructor is the delay. Seems you have that part down. The second argument is the ActionListener that listens for the "Timer Events" (actually ActionEvents). An event is fired each delayed time. The callback (actionPerformed) contains what should be performed after that delay (tick). So whatever you want to happen after that second, put it in the actionPerformed of the timer's ActionListener.
Also if you only want it t occur once, you should call timer.setRepeats(false);. Also note, you are using 10000, which is in milliseconds, so it's 10 seconds, not 1. You should change it to 1000
Example Flow
JButton button = new JButton("Press Me");
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
Timer timer = new Timer(1000, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Print after one second");
}
});
timer.setRepeats(false);
timer.start();
}
});
Press Button → Wait One Second → Print Statement

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.

Timer Task Only Runs Once

How do I make my Timer Task run more than once? This is really bothering me..
timer = new Timer();
timer.schedule(new Client(), 1000);
public void run() {
try {
System.out.println("sent data");
socketOut.write(0);
} catch (Exception e) {
// disconnect client on their side
Game.destroyGame();
timer.cancel();
timer.purge();
}
}
I want this timer to run for an infinite amount of time until the Exception occurs.

When the Javadoc says that it repeats with a specific delay, the delay is the initial delay before the TimerTask starts and not for how long the TimerTask will run. You can repeat the task every period milliseconds. Look at the schedule method. Below is a simple example that repeats every 2 seconds, indefinitely. In the example, the call:
timer.schedule(new RemindTask(seconds), 0, seconds * 1000);
tells timer to run the RemindTask every seconds seconds (*1000 because the time here is really in miliseconds), with an initial delay of 0 - i.e. start the RemindTask right away and then keep repeating at regular intervals.
import java.util.Timer;
import java.util.TimerTask;
public class Main {
static Timer timer;
static int i = 0;
class RemindTask extends TimerTask {
private int seconds;
public RemindTask(int seconds) {
this.seconds = seconds;
}
public void run() {
i+= seconds ;
System.out.println(i + " seconds!");
}
}
public Main(int seconds) {
timer = new Timer();
timer.schedule(new RemindTask(seconds), 0, seconds * 1000);
}
public static void main(String args[]) {
new Main(2);
System.out.format("Task scheduled.%n");
}
}

Looks like to me you're running a GUI program (I'm assuimg SWING, because your other question you were using SWING). So here's a bit of advice. Use a javax.swing.Timer for Swing program.
"How do I make my Timer Task run more than once? "
javax.swing.Timer has methods .stop() and .start() and .restart(). A basic implementation of the Timer object is something like this
Timer timer = new Timer(delay, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
// do something
}
});
timer.start();
You can do anything you want in the actionPerformed and it will fire an event every how many ever milliseconds you provide to the delay. You can have a button call .start() or .stop()
See this answer for a simple implementation of Timer imitating a sort of stop watch for a Boggle game