Multiple calls to AlarmManager.setRepeating deliver the same Intent/PendingIntent extra values, but I supplied different ones

Question

Solved while writing this question, but posting in case it helps anyone:

I'm setting multiple alarms like this, with different values of id:

AlarmManager alarms = (AlarmManager)context.getSystemService(
        Context.ALARM_SERVICE);
Intent i = new Intent(MyReceiver.ACTION_ALARM);  // "com.example.ALARM"
i.putExtra(MyReceiver.EXTRA_ID, id);  // "com.example.ID", 2
PendingIntent p = PendingIntent.getBroadcast(context, 0, i, 0);
alarms.setRepeating(AlarmManager.RTC_WAKEUP, nextMillis, 300000, p);  // 5 mins

...and receiving them like this:

public void onReceive(Context context, Intent intent) {
    if (intent.getAction().equals(ACTION_ALARM)) {
        // It's time to sound/show an alarm
        final long id = intent.getLongExtra(EXTRA_ID, -1);

The alarm is delivered to my receiver at the right times, but often with EXTRA_ID set to the wrong value: it's a value that I have used at some point, just not the one that I wanted delivered at that particular time.

Answer 1

The documentation for PendingIntent.getBroadcast() says:

Returns

Returns an existing or new PendingIntent matching the given parameters.

The problem is that two Intents differing only in extras seem to match for this purpose. So getBroadcast() will return some random old PendingIntent (with a different EXTRA_ID) instead of a new one around the Intent I just created. The fix is to supply a data Uri and make it differ with the id, like this:

Intent i = new Intent(MyReceiver.ACTION_ALARM, Uri.parse("timer:"+id));

You can then retrieve the id number using:

Long.parseLong(intent.getData().getSchemeSpecificPart());

...or of course supply the extra as well and use that.