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Android - how to run a piece of code every minute (synced with the device time) [duplicate]

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How to run a thread repeatedly after some interval
(3 answers)
Closed 4 years ago.
I am developing an Android App in which I need to run a piece of code every minute, when I say every minute I mean it should be synced with the device's time so every time the device time changes by one minute my code is executed.
So far I tried this but it is not working:
runnable=new Runnable(){
#Override
public void run(){
long now=SystemClock.uptimeMillis();
long next=now+(60000 - now % 60000);
handler.postAtTime(this, next);
}
};
runnable.run();

There are many other ways to do this:
1) Timer.scheduleAtFixedRate()
2) Thread.sleep(interval)
3) Alarm Manager
In your way it will look like this:
final Handler handler = new Handler();
Runnable runnable = new Runnable() {
#Override
public void run() {
try{
//do your code here
}
catch (Exception e) {
// TODO: handle exception
}
finally{
//also call the same runnable to call it at regular interval
handler.postDelayed(this, "*interval");
}
}
};
handler.postDelayed(runnable, "*interval");
you can see this answer for details

You can use this code:
Thread thread = new Thread(new Runnable()
{
int lastMinute;
int currentMinute;
#Override
public void run()
{
lastMinute = currentMinute;
while (true)
{
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
currentMinute = calendar.get(Calendar.MINUTE);
if (currentMinute != lastMinute){
lastMinute = currentMinute;
Log.v("LOG", "your code here");
}
}
}
});
thread.run();

one can use handle and can give input as milliseconds and we can call the code for every minute and should not use any infinite loops while using two different layouts
final Handler handler = new Handler();
Runnable run = new Runnable() {
#Override
public void run() {
handler.postDelayed(this, 60000);
}
};
handler.post(run);

You can use handler if you want to initiate something every X seconds. Handler is good because you don't need extra thread to keep tracking when firing the event. Here is a Code:
private final static int INTERVAL = 1000 * 60 * 1; //1 minutes
Handler mHandler = new Handler();
Runnable mHandlerTask = new Runnable()
{
#Override
public void run() {
doSomething();
mHandler.postDelayed(mHandlerTask, INTERVAL);
}
};
void startRepeatingTask()
{
mHandlerTask.run();
}
void stopRepeatingTask()
{
mHandler.removeCallbacks(mHandlerTask);
}

The modern method
new Handler().postDelayed(() -> {
}, 30000);

Scheduling java process for a specific time interval with a given delay

We want to schedule a java process to run till a specific time interval. Currently I am thinking to using TimerTask to schedule this process. In the start of every loop, will check the current time and then compare with the given time and stop the process if the time is elapsed.
Our code is something like below:
import java.util.Timer;
import java.util.TimerTask;
public class Scheduler extends TimerTask{
public void run(){
//compare with a given time, with getCurrentTime , and do a System.exit(0);
System.out.println("Output");
}
public static void main(String[] args) {
Scheduler scheduler = new Scheduler();
Timer timer = new Timer();
timer.scheduleAtFixedRate(scheduler, 0, 1000);
}
}
Is there a better approach for this?

Instead of checking if the time limit has been reached in every single iteration you could schedule another task for the said time limit and call cancel on your timer.
Depending on the complexity you might consider using a ScheduledExecutorService such as ScheduledThreadPoolExecutor. See in this answer when and why.
Simple working example with timer:
public class App {
public static void main(String[] args) {
final Timer timer = new Timer();
Timer stopTaskTimer = new Timer();
TimerTask task = new TimerTask() {
#Override
public void run() {
System.out.println("Output");
}
};
TimerTask stopTask = new TimerTask() {
#Override
public void run() {
timer.cancel();
}
};
//schedule your repetitive task
timer.scheduleAtFixedRate(task, 0, 1000);
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sdf.parse("2015-06-09 14:06:30");
//schedule when to stop it
stopTaskTimer.schedule(stopTask, date);
} catch (ParseException e) {
e.printStackTrace();
}
}
}

You can use RxJava, a very powerful library for reactive programming.
Observable t = Observable.timer(0, 1000, TimeUnit.MILLISECONDS);
t.subscribe(new Action1() {
#Override
public void call(Object o) {
System.out.println("Hi "+o);
}
}
) ;
try {
Thread.sleep(10000);
}catch(Exception e){ }
You can even use the lambda syntax:
Observable t = Observable.timer(0, 1000, TimeUnit.MILLISECONDS);
t.forEach(it -> System.out.println("Hi " + it));
try {
Thread.sleep(10000);
}catch(Exception e){ }

Creating a timer and cannot restart it

I've created GUI timer, it runs exactly how I wanted it to. I have a stop and pause button, when I stop or pause the timer and restart a new one I get Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Task already scheduled or cancelled
I'm unsure what I'm suppose to do I've read you cant reuse tasks, but I have no clue to solve this. Can someone PLEASE help me out I'm going crazy over this, I always seem to fix one problem but another one pops up.
Heres part of my code which does the countdown
private TimerTask task = new TimerTask(){
#Override
public void run(){
if (countdown()) {
if(minutes < 9 && seconds < 9)
timerOutput.setText("0"+minutes + ": 0" + seconds);
else if(minutes < 9)
timerOutput.setText("0"+minutes + ":" + seconds);
else if(seconds < 9)
timerOutput.setText(minutes + ": 0" + seconds);
}
else
{
System.out.println("Finish!");
timerOutput.setText("Time is up!");
timer.cancel();
startBut.setEnabled(true);
}
}
};
private boolean countdown(){
seconds --;
if (seconds < 0){
minutes--;
seconds = 59;
if (minutes == -1){
return false;
}
}
return true;
}

Well TimerTasks aren't designed to be reused. The best you can do is create a new TimerTask every time you're going to reschedule it.

Although you can't simply restart a Timer, you could create a Timer wrapper class which would act exactly like a Timer but allow a simple restart method that would instantiate a new Timer in the background. For example;
public class RestartableTimer{
private Timer timer;
private long delay, period;
public RestartableTimer(){
timer = new Timer();
}
public void scheduleAtFixedRate(TimerTask task, long delay, long period){
this.delay = delay;
this.period = period;
timer.scheduleAtFixedRate(task, delay, period);
}
public void restart(TimerTask task){
timer.cancel();
timer = new Timer();
timer.scheduleAtFixedRate(task, delay, period);
}
}
A fair warning, this would not allow for polymorphism. You couldn't for example store a RestartableTimer in a Timer reference. You will also still need to instantiate a new TimerTask when you restart. If you wanted (and you knew you would only be reusing the same TimerTask), you could declare a custom and private embedded class in the above and let the wrapper class handle the creation of the new TimerTask. Alternatively you could have the class methods take a TimerTaskFactory which would implement an Interface which required a method that returned a TimerTask.
Below, an example of using the above class;
public static void main(String[] args) throws InterruptedException{
TimerTask task = new TimerTask(){
#Override
public void run() {
System.out.println("Running");
}};
RestartableTimer rt = new RestartableTimer();
System.out.println("Timer starting with one task");
rt.scheduleAtFixedRate(task, 1000, 1000);
Thread.sleep(5000);
System.out.println("Timer restarting with another task");
rt.restart(new TimerTask(){
int count = 0;
#Override
public void run() {
if(count>4) {
System.out.println("Done");
this.cancel();
} else {
System.out.println("Running 2");
count++;
}
}});
}

how to put a timer on a JLabel to update itself every second

I created a game and in my swing GUI interface I want to put a timer. The way I do this at the moment is have a field with the current time , gotten with System.currentTimeMillis() which gets it's value when the game starts .In the method of my game i put the System.currentTimeMillis()- field; and it tells you the current time passed since the game started.
Nevertheless, how do get this to update itself every second lets say, so the JLabel will have : timePassed: 0s , timePassed: 1s and so on. Have in mind that i don't use threads in my game at any point.
EDIT: thank you all for your kind suggestions. I used a combination of your answers please give me some feedback.
I have the JLabel as a field called time. (else i cant handle it).
time = new JLabel("Time Passed: " + timePassed() + " sec");
panel_4.add(time);
ActionListener actionListener = new ActionListener() {
public void actionPerformed(ActionEvent actionEvent) {
time.setText("Time Passed: " + timePassed() + " sec");
}
};
Timer timer = new Timer(1000, actionListener);
timer.start();

Have a look at the swing timer class. It allows to setup recurring tasks quite easily.

This is how I would set my JLabel to update with time & date.
Timer SimpleTimer = new Timer(1000, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
jLabel1.setText(SimpleDay.format(new Date()));
jLabel2.setText(SimpleDate.format(new Date()));
jLabel3.setText(SimpleTime.format(new Date()));
}
});
SimpleTimer.start();
This is then added to your main class and the jlabel1/2/3 get updated with the timer.

new Thread(new Runnable
{
public void run()
{
long start = System.currentTimeMillis();
while (true)
{
long time = System.currentTimeMillis() - start;
int seconds = time / 1000;
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
label.setText("Time Passed: " + seconds);
}
});
try { Thread.sleep(100); } catch(Exception e) {}
}
}
}).start();

wirite this in Constructor
ActionListener taskPerformer = new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
jMenu11.setText(CurrentTime());
}
};
Timer t = new Timer(1000, taskPerformer);
t.start();
And this Write out Constructor
public String CurrentTime(){
Calendar cal = new GregorianCalendar();
int second = cal.get(Calendar.SECOND);
int min = cal.get(Calendar.MINUTE);
int hour = cal.get(Calendar.HOUR);
String s=(checkTime(hour)+":"+checkTime(min)+":"+checkTime(second));
jMenu11.setText(s);
return s;
}
public String checkTime(int t){
String time1;
if (t < 10){
time1 = ("0"+t);
}
else{
time1 = (""+t);
}
return time1;
}

Calling a function every 10 minutes

I'm not an expert, just a beginner. So I kindly ask that you write some code for me.
If I have two classes, CLASS A and CLASS B, and inside CLASS B there is a function called funb(). I want to call this function from CLASS A every ten minutes.
You have already given me some ideas, however I didn't quite understand.
Can you post some example code, please?

Have a look at the ScheduledExecutorService:
Here is a class with a method that sets up a ScheduledExecutorService to beep every ten seconds for an hour:
import static java.util.concurrent.TimeUnit.*;
class BeeperControl {
private final ScheduledExecutorService scheduler =
Executors.newScheduledThreadPool(1);
public void beepForAnHour() {
final Runnable beeper = new Runnable() {
public void run() { System.out.println("beep"); }
};
final ScheduledFuture<?> beeperHandle =
scheduler.scheduleAtFixedRate(beeper, 10, 10, SECONDS);
scheduler.schedule(new Runnable() {
public void run() { beeperHandle.cancel(true); }
}, 60 * 60, SECONDS);
}
}

import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
public class ClassExecutingTask {
long delay = 10 * 1000; // delay in milliseconds
LoopTask task = new LoopTask();
Timer timer = new Timer("TaskName");
public void start() {
timer.cancel();
timer = new Timer("TaskName");
Date executionDate = new Date(); // no params = now
timer.scheduleAtFixedRate(task, executionDate, delay);
}
private class LoopTask extends TimerTask {
public void run() {
System.out.println("This message will print every 10 seconds.");
}
}
public static void main(String[] args) {
ClassExecutingTask executingTask = new ClassExecutingTask();
executingTask.start();
}
}

Try this. It will repeat the run() function every set minutes. To change the set minutes, change the MINUTES variable
int MINUTES = 10; // The delay in minutes
Timer timer = new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() { // Function runs every MINUTES minutes.
// Run the code you want here
CLASSB.funcb(); // If the function you wanted was static
}
}, 0, 1000 * 60 * MINUTES);
// 1000 milliseconds in a second * 60 per minute * the MINUTES variable.
Don't forget to do the imports!
import java.util.Timer;
import java.util.TimerTask;
For more info, go here:
http://docs.oracle.com/javase/7/docs/api/java/util/Timer.html
http://docs.oracle.com/javase/7/docs/api/java/util/TimerTask.html

public class datetime {
public String CurrentDate() {
java.util.Date dt = new java.util.Date();
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String currentTime = sdf.format(dt);
return currentTime;
}
public static void main(String[] args) {
class SayHello extends TimerTask {
datetime thisObj = new datetime();
public void run() {
String todaysdate = thisObj.CurrentDate();
System.out.println(todaysdate);
}
}
Timer timer = new Timer();
timer.schedule(new SayHello(), 0, 5000);
}
}

Solution with Java 8
ClassB b = new ClassB();
ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
Runnable task = () -> {
b.funb();
};
executor.scheduleWithFixedDelay(task, 0, 10, TimeUnit.MINUTES);