Question

I’m new in this whole Android environment and I usually have some doubts that maybe you can consider very basic knowledge and a bit stupid. I will try to do my best explaining the doubt I have and why i have it to make me understand.

I’m doing an application where you can set notifications to remind you the scholar classes you want. I have done a class that extends BroadcastReceiver so it can reset all the alarms after the device has booted. I have a database where I keep information about the alarms: the class, the time it has to be configured, etc. I retrieve all the alarms and set them to the alarmManager this way:

intent = new Intent(ctxt.getApplicationContext(), Notificacion.class);
intent.putExtra("TAG", tag);
intent.putExtra("SUBJECT", cursor2.getString(0));
intent.putExtra("AULA", cursor2.getString(1));                  
displayIntent = PendingIntent.getBroadcast(ctxt, Integer.parseInt(tag), intent, PendingIntent.FLAG_UPDATE_CURRENT );               
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY*7, displayIntent);

Well, I guess this should work fine until here. The problem is that when you use the app and you want to set a notification, you are doing it from the class “Schedule.class” so the intent would have this context:

Intent intent = new Intent(getApplicationContext(), Notification.class);
PendingIntent pend = PendingIntent.getBroadcast(this, Integer.parseInt(tag), intent, PendingIntent.FLAG_UPDATE_CURRENT);

In the app, you can delete an alarm, and you have to call alarmManager.cancel(pend) in order to do that. So my doubt is if it will be able to cancel it.

If the contexts are different, it won’t find the match with the pending intent, because it was set from the context I got in my extension of BroadCastReceiver (ctxt), and the alarm was set with the context I got from Schedule.class.

So.. is the application context always the same? I know that the context is set in order to give information to other classes about what has been going on, but I’m not sure if the Intent filter will differentiate where the context was given.

Thank you in advance!

Answer 1

Looking at the AlarmManager documentation for the cancel method you’re using:

public void cancel (PendingIntent operation)

Added in API level 1

Remove any alarms with a matching Intent. Any
alarm, of any type, whose Intent matches this one (as defined by
filterEquals(Intent)), will be canceled.

So, the Intent.filterEquals documentation says the following:

public boolean filterEquals (Intent other)

Added in API level 1

Determine if two intents are the same for the
purposes of intent resolution (filtering). That is, if their action,
data, type, class, and categories are the same. This does not compare
any extra data included in the intents.

I can’t think of any reason why the action, data, type, class, or category would be different from one explicit Intent to another (unless, obviously you went out of your way to change those things). The contexts do not appear to be in the criteria for the matching, so I think you can be fairly confident that it will be cancelled no matter which context was used to create it in the first place.