Question

When I run my application for the first time my alarm is started and it works very well.

Intent intent = new Intent(this, Kill_Task.class);  
PendingIntent pendingIntent = PendingIntent.getBroadcast(
                   this, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);  

AlarmManager objAlarmManager = 
     (AlarmManager) getSystemService(Context.ALARM_SERVICE);  
objAlarmManager.setRepeating(
     AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 1000, pendingIntent);

Now my alarm is continuing in background and I have to switch off my phone. When I switch on my phone my alarm background processing does not start.

Why is this?

Answer 1

1) your alarm repeat every second your defined pending intent object . AlarmManager.setRepeating(...
2) to cancel/stop your alarm you’ve to invoke objAlarmManager.cancel(pendingIntent); . with a pendingIntent that match your pending intent that you’ve define (same class, same action … except extra data that is not taking into account for comparizon … see IntenFilter to know more about how intent may match another one
3) then cancel the pending intent itself like pendingIntent.cancel(); to be sure that pending intent is unusable.