How to save scheduled alarm after app was killed by Android or task killer?

Question

Code that schedules alarm.

    PendingIntent sender = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager am =          


        

Answer 1

Alarm set by alarm manager is not killed when app is closed, how ever when a reboot occurs all alarms are cleared by the os since there is no persistence. So you need to do the persistence.

• Every Time while setting a alarm save the alarm time.
• Register a receiver for boot completion.

• Set the alarm again on reboot.

  public class BootReceiver extends BroadcastReceiver {
  
      @Override
      public void onReceive(Context context, Intent intent) {
          //re register the alarm
     }
  }
  

Manifest.xml

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
.......
<receiver
      android:name="BootReceiver"
        android:enabled="true"
        android:exported="true"
        >
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </receiver>

You could use SharedPreference to save the time (time at when the alarm should be triggered or time at when it should be triggered next)

Use that to set a new alarm at the boot receiver.

Answer 2

have your application broadcast a message as its being killed, and when this message is broadcast, then have a listener check if the service is still running.. if its not run it. This will insure that your service is running even if the application is killed.

Update

I'll try to create a flow diagram for you

The onDestroy() method is part of a service.

I hope this helps.

UPDATE 2

One thing I forgot to mention is the fact that you ideally only want one instance of the service to be run. So just looking at the ID that is present within the onStart() should be == to 1 to start it else.. ignore it.

Methods of notice of the Service Class:

onStart() : This method is called when the service is being started

onDestroy() : This is the method that is called when a service is being killed

Methods of notice of the BroadcastReciever class:

onReceive(): This methods receives all intents that are sent to it (unless filtered)

Look up examples on BroadcastRecievers (Message Broadcasting) and Service (Starting a service)

References:

http://developer.android.com/reference/android/content/BroadcastReceiver.html

http://developer.android.com/reference/android/app/Service.html