Develop Reference

Android AlarmManager is not triggering alarm on next day when idle

I know there are dozens of similar threads on SO about this topic but I just couldn't find one that really solves the problem / or identifies the root cause.
First of all, I'm targetting SDK 22 (Android 5.1) which means I could use the AlarmManager + WakefulBroadcastReceiver + IntentService even if this is not the latest way of doing things.
I'm not interested in the JobScheduler etc solutions, I just want to understand what is happening and why.
The phone I'm testing on has Android 8.0, but it shouldn't matter as I'm targeting Android 5.1.
So the code I'm dealing with sets the alarm for the next day, 06:00.
private fun setupAlarm() {
val calendar = Calendar.getInstance()
calendar.timeInMillis = System.currentTimeMillis()
calendar.add(Calendar.DAY_OF_YEAR, 1)
calendar.set(Calendar.HOUR_OF_DAY, 6)
calendar.set(Calendar.MINUTE, 0)
val alarmIntent = Intent(this, AlarmReceiver::class.java)
val alarmPendingIntent = PendingIntent.getBroadcast(this, 1221, alarmIntent, PendingIntent.FLAG_UPDATE_CURRENT)
val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.timeInMillis, AlarmManager.INTERVAL_DAY, alarmPendingIntent)
}
The AlarmReciever only starts a service:
class AlarmReceiver : WakefulBroadcastReceiver() {
override fun onReceive(context: Context?, intent: Intent?) {
startWakefulService(context, Intent(context, DownloadingIntentService::class.java));
}
}
This Service then tries to download a file, when finished it calls the completeWakefulIntent(intent) method letting know the system that it's done with its job.
I could not figure out when it is working and when it is not. One morning it did what it should have, on the other, it didn't.
I set up a remote LogCat feature to see whether the IntentService is started but so far I can't see any logs from it, so it means that the alarm is not triggered.
If I set up an alarm for the next minute, even repeating one whatever it works like it should. But when I set back the time for tomorrow morning then it's very unreliable.
Thanks for your help.

I've faced this exact issue myself. See what happens is that setRepeating method let's the android system adjust the time when the alarm should get fired. It will most likely try to batch different alarms in order to optimise battery usage. But in regular cases, if the phone isn't dozing... It generally fires the alarm at correct times.
However if the phone has been idle for a time, the phone goes into doze mode and due to this the alarm gets delayed. I have personally observed delays of upto 1 1:30 hours.
If you want it to fire exactly, you'll have to use the setExactAndAllowWhileIdle method or setAlarmClock method. In this case, you will have to handle the scheduling of your next alarm on your own. The methods work well with doze mode and do fire the alarms at exact times.
There are cons to these methods too. The setExactAndAllowWhileIdle method can only be used to schedule alarms Max once per nine minutes or so. The setAlarmClock method will mostly show a notification like a regular alarm to the user and will indicate the details of the alarm ( this behaviour varies with different os versions )

I used this code to trigger a backup every day. It is working for me, Give it a try.
AlarmManager alarmMgr = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, MyReceiver.class);
intent.setAction("CUSTOM_INTENT");
alarmIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.set(Calendar.HOUR_OF_DAY, 06);
calendar.set(Calendar.MINUTE, 00);
// setRepeating() lets you specify a precise custom interval--in this case,
// 1 day
alarmMgr.setRepeating(AlarmManager.RTC, calendar.getTimeInMillis()/1000,
AlarmManager.INTERVAL_DAY, alarmIntent);

Try this:
Calendar now = Calendar.getInstance();
Calendar alarm = Calendar.getInstance();
alarm.set(Calendar.HOUR_OF_DAY, hourOfDay);
alarm.set(Calendar.MINUTE, minute);
long alarmMillis = alarm.getTimeInMillis();
if (alarm.before(now)) alarmMillis+= 86400000L; //It will add 1 day if your time selected before now
//set alarm method of yours\\
settingAlarmManager(requestCode, alarmMillis);
private void settingAlarmManager(String requestCode, Calendar calendar) {
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent notificationIntent = new Intent(AddTaskActivity.this, AlarmReceiver.class);
PendingIntent broadcast = PendingIntent.getBroadcast(AddTaskActivity.this,
Integer.valueOf(requestCode), notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);
alarmManager.setInexactRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, broadcast);
}
My Receiver class:
public class AlarmReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
//do your stuff here\\
}
}
Manifest:
<receiver android:name=".utils.AlarmReceiver" />
I have tried above code for setting alarm and do my custom task. Maybe this will help you.

A few things:
The further in time an Alarm is scheduled, the less precise it will be.
Although you are targeting API Level 22, deprecated elements in higher Android version may not fully work, which is the case of the WakefulBroadcastReceiver
You are trying to run a background job in Android 8.0. It's worth exploring the Foreground Service:
It can be started from the background
Correctly notify users that you are indeed doing something while the phone should be idle.
Do not fear running tasks that might take a few seconds to complete.
You might have killed your application. When a user manually kills an app, in most devices all Alarm's and PendingIntent's are killed as well.
A scheduling strategy many developer use is not to set a repeating Alarm, yet have two single Alarms that reschedule each other continuously ( #Kushan mentioned something similar in his answer).
In short:
Have a Scheduler start as soon as possible during the day (even when a user opens your app, it can be fired multiple times). Check if the desired PendingIntents already exist (your background jobs). If they do not, just schedule them. As well, schedule another Alarm around 11.55.
All this midnight scheduler has to do, is to re-schedule the main AlarmManager in 5 minutes, which is then going to schedule the jobs and the midnight alarm for the next days.
This method allows you to:
schedule exact alarms, since repeating ones do not have the exact option.
reduce the time distance of your scheduled alarms, which will then generally be treated with more precision by the OS.
avoid alarms that trigger immediately because scheduled in the past
Also, try to get the most from the API version you are using:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
this.alarmManager.setExactAndAllowWhileIdle(
AlarmManager.RTC_WAKEUP,
rtcStartingTime.getTimeInMillis(),
pendingIntent
);
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
this.alarmManager.setExact(
AlarmManager.RTC_WAKEUP,
rtcStartingTime.getTimeInMillis(),
pendingIntent
);
} else {
this.alarmManager.set(
AlarmManager.RTC_WAKEUP,
rtcStartingTime.getTimeInMillis(),
pendingIntent
);
}

Alarm Manager Not Firing

In my code the Interval ( third parameter) on setRepeating() method seems not firing every 5 sec .
It keeps increasing in time, it's like the first one or 2 are mostly in time but the others fires like after 40+secs
So what's wrong here?
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent i = new Intent(this, MainActivity2Activity.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pi = PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager am = (AlarmManager) getSystemService(Context.ALARM_SERVICE );
am.setRepeating(RTC_WAKEUP,System.currentTimeMillis(),1000*5,pi);
}
}

Take a look here: http://developer.android.com/reference/android/app/AlarmManager.html#setRepeating(int, long, long, android.app.PendingIntent)
As you're firing alarm every 5 seconds:
Note: for timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler.
Your code is ok. Explanation of a delay you're experiencing may be:
Note: as of API 19, all repeating alarms are inexact. If your application needs precise delivery times then it must use one-time exact alarms, rescheduling each time as described above. Legacy applications whose targetSdkVersion is earlier than API 19 will continue to have all of their alarms, including repeating alarms, treated as exact.

From what I understand from your code you are trying to run MainActivity2Activity.class 5 seconds after the creation of MainActivity.class.
I would advice you to use FLAG_UPDATE_CURRENT instead of FLAG_CANCEL_CURRENT in your pending intent.
The FLAG_CANCEL_CURRENT would retain your first ever pending intent and won't update or create a new one until and unless you cancel the original pending intent first.
Using FLAG_UPDATE_CURRENT will ensure that the pending intent is updated every time MainActivity.class is executed, so that pending intent will be fired exactly after 5 seconds the MainActivity.class is created.
Hope this helps.

Basically you wrote PendingIntent.FLAG_CANCEL_CURRENT instead of PendingIntent.FLAG_ONE_SHOT.
Code for Set Alarm by Alarm Manager
AlarmManager alarmManager = (AlarmManager) getBaseContext().getSystemService(ALARM_SERVICE);
Intent i1 = new Intent(this, ReceiveAlarmActivity.class);
i1.putExtra("Key", "Value");
PendingIntent operation = PendingIntent.getActivity(getBaseContext(), 0, i1, PendingIntent.FLAG_ONE_SHOT);
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, Your_Date.getTime(), 5000 operation);
You have to pass Your Date.
Done

Calendar instance in android for AlarmManager

I am developing an app which displays notifications by using AlarmManager.
For that I'm taking the user input values for hour, minute and second.
Something like:
int hour = 4;
int min = 40;
int sec =36
Calendar Calendar_Object = Calendar.getInstance();
Calendar_Object.set(Calendar.HOUR, hour);
Calendar_Object.set(Calendar.MINUTE, min);
Calendar_Object.set(Calendar.SECOND, sec);
Intent myIntent = new Intent(MyView.this, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(MyView.this,0, myIntent, 0);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.set(AlarmManager.RTC, Calendar_Object.getTimeInMillis(), myIntent);
Notifications and the rest of the code work fine, but the problem is that instead of 4:40:36 the notifications get invoked on the current time(as soon as i run/debug the app).
I think there is some problem in Calender_Object part.
Looking for a solution.
Thanks in advance.

Please note: Alarms will be executed immediately, if the notification time has elapsed already.
As a workaround you might want to consider a date part too. Or just a variable in memory which acts as a boolean if the time has elapsed or not.
From the Docs:
If the stated trigger time is in the past, the alarm will be triggered immediately. If there is already an alarm for this Intent scheduled (with the equality of two intents being defined by filterEquals(Intent)), then it will be removed and replaced by this one.
Also please consider the API level 19 version of how AlarmManager works.

Android: Resetting repeating AlarmManager from within called service

I've set a repeating alarm on a service and decided that it's most convenient to reset the alarm from within the called service. The reason is that the service already has code to check if it's within a user-defined schedule (time range). When it's outside the time range, it resets the alarm to start at the future time selected by the user. Maybe I'm approaching this wrong but I'll put this question out there and see what you think.
An activity kicks off the service by creating a repeating alarm:
//Activity
Calendar cal = Calendar.getInstance();
Intent intent = new Intent(getApplicationContext(), MyService.class);
intent.setData(Uri.parse("MyService://identifier"));
PendingIntent pIntent = PendingIntent.getService(getApplicationContext(), 0, intent, 0);
AlarmManager alarm = (AlarmManager)getSystemService(ALARM_SERVICE);
alarm.setInexactRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(),
intervalInMins*60000, pIntent);
The service has something like this:
//Service
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Uri Action = intent.getData();
try {
if (Action.equals(Uri.parse("MyService://identifier"))) {
//Simplifying the code here: CalculatedOffset is determined from the current time
//and scheduled start time. intervalInMins is read from settings.
if (!WithinSchedule()) {
Calendar cal = Calendar.getInstance();
PendingIntent pIntent = PendingIntent.getService(getApplicationContext(), 0, intent, 0);
AlarmManager alarm = (AlarmManager)getSystemService(ALARM_SERVICE);
alarm.setInexactRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis() + CalculatedOffset,
intervalInMins*60000, pIntent);
}
}
} catch (NullPointerException np) {
np.printStackTrace();
}
return Service.START_REDELIVER_INTENT;
}
I was hoping to re-use the intent to reset the repeating alarm. With this new code, I'm seeing multiple alarms stack up firing rapidly in succession around when the start time hits. It should not spaz out like that, but should fire at regular intervals as it did before the scheduling reset. I need to catch it in the debugger but haven't been able to determine the exact conditions yet. Is my understanding of alarms completely off base here? Is there a better way to do this?
Addendum: A wrinkle in this is that I'm using RootTools to gain superuser privileges in order to work around Android 4.2's airplane mode. This hasn't been a problem before the scheduling, but I'm suspicious whether su is blocking for a long time while the alarms stack up.

Re-using the intent inside the service that receives the alarm does work. I've switched from using a Repeating Alarm to a single-shot alarm which gets re-armed every time the service is called. Unfortunately this didn't fix the problem of the alarms stacking. The culprit is definitely su blocking. It may be RootTools or su itself. I need to update the library from 2.6 to 3.x and see if that makes any difference.

Android repeating alarm not working

This works fine:
Intent intent = new Intent(HelloAndroid2.this, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(HelloAndroid2.this, 0,
intent, PendingIntent.FLAG_ONE_SHOT);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + (12 * 1000), pendingIntent);
This doesn't work. I hear the alarm only time.
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + (12 * 1000), 3 * 1000, pendingIntent);
I have also tried this, no luck:
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.add(Calendar.SECOND, 5);
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), 7000, pendingIntent);
What is the problem?

From the PendingIntent doc for FLAG_ONE_SHOT:
this PendingIntent can
only be used once. If set, after
send() is called on it, it will be
automatically canceled for you and any
future attempt to send through it will
fail.
So after the pendingIntent is fired the first time, it will be cancelled and the next attempt to send it via the alarm manager will fail
Try using FLAG_UPDATE_CURRENT

Looking at your code samples in order:
In your first sample you are using AlarmManager.set - this is strictly for one-off alarms so yes, it will only fire once. If you want to use AlarmManager.set then the last thing the code triggered should do is to set a fresh alarm (which should also use a fresh PendingIntent).
In your second example you are using a repeating alarm. You do not need to create a fresh PendingIntent each time this fires as the OS takes care of the repeating aspect of the alarm.
There is no reason why your alarm should not repeat every 3 seconds, so I would start looking at the BroadcastReceiver implementation you have written to handle the alarm.
Check that you've implemented it properly. Comment out all the code in the onReceive() method and instead just have it writing a log message. Once you see your log message appearing in the logcat every time the alarm fires, add your code back in (keeping the log message), and another log message to the end of the method. This allows you to see how long the method takes to execute - you want it to be finished before the alarm fires again to avoid any unexpected side effects.
As an aside, if you want a repeating alarm, android.os.Handler is a much more efficient approach although alarms set through AlarmManager do fire very accurately.