Develop Reference

Can AlarmManager schedule more than one alarm from the same code?

If I allow my user to schedule a notification using AlarmManager, and then they schedule another notification using the same code, will the first alarm be overridden? Or will both alarms be set?

When creating a pendingIntent you have to include an id:
PendingIntent pendingIntent = PendingIntent.getBroadcast(this, ID , intent, Flags)
If the number in the ID location is always the same, then the alarm will be overridden. If it is the same then it will not be.
You can use the same code, as long as the ID is different. You can achieve this in many ways, like creating an ID based on the time you schedule the alarm for, as you may not need two alarms for the same time.

Deleteing alarms in alarm manager

For example, i have a calendar, which allows user to set every day alarm. For this function i took alarm manager's method setRepeating(). But my problem comes when user wants to delete alarm from specific day, but not deleting all alarms. How can i make that? Is alarm manager the only way to set alarms? Any ideas will be appreciated.
Cleverest thing i came up - to set broadcast receiver which will trigger every day at 00:00 and set all alarms by method alarmManager.set(). Deleted alarms will be at database and if today alarm will match to deleted one - broadcast receiver will not set this alarm.

AlarmManager has a method cancel(); and it may help you. But in your case I would have been more confident with going the approach you given as a hind in your question.

you can use .cancel() method of Alarm manager..But remember one thing.You have to give the same id in the pending intent that you supply to the alarm manager to that you had set the alarm with.
PendingIntent pendingIntent = PendingIntent.getBroadcast(getContext(),id,intent, PendingIntent.FLAG_CANCEL_CURRENT);
alarmManager.cancel(pendingIntent);
the id supplied should be the same that was used to set the alarm.
I hope that will help you..
I would suggest you to save the id for each alarms somewhere and use it to cancel it if you need to.

Android setting multiple long date alarms

I'm trying to create a function in my App, which notifies the user at the expiration day of his rented books. I'll work with checkboxes in a listview, as below:
(Dates are for show purposes only)
Now i'm wondering how can i do it the best way. I'm having experiences with AlarmManager and BroadcastReceivers, but I didn't get a clear flowchart yet.
Thats because I need to set an specific alarm to each book and cancel that specific alarm when requested. Also, it needs to reactivate all Alarms when device is restared (by calling BOOT_COMPLETE broadcast).
PS.: Alarms will usually be set to one week after current date.
PS2.: Can I use Calendar to do it? I mean, this way i wouldn't have to reactivate all alarms, or calculate (expirationDate - currentDate) in millis.
Can someone, who has an idea, try to show me the way? Thanks!

I think the key would be to give each and every book its own alarm id as soon as you set the alarm for this book for the first time.
Then you should keep a list of the running alarm ids and timestamps (maybe in SharedPreferences).
With a method like this you can cancel a specific alarm with regards to its alarm id:
public static void cancelAlarm(Context context, int alarmId) {
PendingIntent pi = PendingIntent.getService(context, alarmId,
new Intent(context, YourService.class),
PendingIntent.FLAG_NO_CREATE);
if(pi!=null) {
AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
am.cancel(pi);
}
}
When you receive the BOOT broadcast, you can get the list of alarm ids together with timestamps from SharedPreferences and start all the alarms with their respective alarm ids

Android - How to reschedule alarms associated to app events

I found a lot of examples and questions regarding how to fire an alarm using AlarmManager (both periodical or single), but nothing similar to what I need.
My user can schedule a certain number of events (i.e. things to do), with a single-shot alarm for each of them to be fired one day before the scheduled start (showing a notification). This is easy.
My problem is that this scheduled start can be changed, thus the alarm should be moved too.
I was thinking to delete the old alarm, and to create a new one considering the new scheduled start. Knowing that I can delete an alarm using alarmMgr.cancel(alarmIntent), how can I delete the specific alarm related to the rescheduling event? Should I make each alarmIntent unique in some way?
Or there is a better way that I didn't consider (except using Google Calendar APIs to schedule and reschedule an event there, and making it managing the notification)?

While scheduling an alarm using set() API
public void set (int type, long triggerAtMillis, PendingIntent operation)
in the last argument you can mention a request code using getBroadcast
public static PendingIntent getBroadcast (Context context, int requestCode, Intent intent, int flags)
an example for this would be :
alarm.set(AlarmManager.RTC_WAKEUP, time, PendingIntent.getBroadcast(mContext, id, intentAlarm, PendingIntent.FLAG_UPDATE_CURRENT));
When you want to cancel or reschedule you can use the 'id' to specify which alarm.

Android Alarm Clock - Remove alarms programmatically

I am writing an application in which user can configure alerts/alarms. At this point, I have everything working expect the one. I am firing off an alarm using
Intent alarmIntent = new Intent(AlarmClock.ACTION_SET_ALARM);
alarmIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
alarmIntent.putExtra(AlarmClock.EXTRA_MESSAGE, "Some message!");
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.MINUTE, 1);
alarmIntent.putExtra(AlarmClock.EXTRA_HOUR, calendar.get(Calendar.HOUR_OF_DAY));
alarmIntent.putExtra(AlarmClock.EXTRA_MINUTES, calendar.get(Calendar.MINUTE));
alarmIntent.putExtra(AlarmClock.EXTRA_SKIP_UI, true);
context.startActivity(alarmIntent);
I want to remove this alarm once user has dismissed using the Dismiss button. I can see the alarms being still there in the alarm clock which I set using above code through my application.
Is there some way to get a cursor or something similar on the alarms being there in the alarm clock? This will help me iterate over them and remove the ones I want.
Any help would be appreciated, Thanks in advance.

As it was answered here: there is no supported API to this.
Official documentation says that
If a time of day is specified, and EXTRA_SKIP_UI is true, and the
alarm is not repeating, the implementation should remove this alarm
after it has been dismissed.
But different manufactures implement their own alarm clocks and I'm not sure if someone supporrts this.
I have tried it on JB emulator and looks like it dosen't work. Maybe, on KitKat?
Only this one is ok on JB:
If an identical alarm exists matching all parameters, the implementation
may re-use it instead of creating a new one
So, maybe, better solution is to use youre own alarm, created with AlarmManager or warn user that he has to remove Alarms by hands (to make it more obvious - not use AlarmClock.EXTRA_SKIP_UI).

call method cancel(...) from AlarmManager, using the same PendingIntent you used to set the alarm. Example:
mAlarmPendingIntent = PendingIntent.getActivity(this, requestCode, intent, flags);
this.getAlarmManager().cancel(mAlarmPendingIntent);
this refers to the Activity or the Service from which you are cancelling the alarm