What's "requestCode" used for on PendingIntent?
requestCode
is used to retrieve the same pending intent instance later on (for cancelling, etc).- Yes, my guess is the alarms will override each other. I would keep the request codes unique.
I just want to add to @Minhaj Arfin answer
1- requestCode is used to get the same pending intent later on (for cancelling etc)
2- Yes, they will get override as long as your specify the same Receiver to your Intent that you specify on your PendingIntent
example:
Intent startIntent1 = new Intent(context, AlarmReceiverFirst.class);
PendingIntent pendingIntent1 = PendingIntent.getBroadcast(context, 0, startIntent1, 0);
Intent startIntent2 = new Intent(context, AlarmReceiverSecond.class);
PendingIntent pendingIntent2 = PendingIntent.getBroadcast(context, 0, startIntent2, 0);
From above example, they will not override each other because the receiver is different(AlarmReceiverFirst and AlarmReceiverSecond)
Intent startIntent2 = new Intent(context, AlarmReceiverSecond.class);
PendingIntent pendingIntent2 = PendingIntent.getBroadcast(context, 0, startIntent2, 0);
Intent startIntent3 = new Intent(context, AlarmReceiverSecond.class);
PendingIntent pendingIntent3 = PendingIntent.getBroadcast(context, 0, startIntent3, 0);
From above example, they will override each other, because the receiver is same(AlarmReceiverSecond)
Actually, the documentation clearly states what the request code is used for:
If you truly need multiple distinct PendingIntent objects active at the same time (such as to use as two notifications that are both shown at the same time), then you will need to ensure there is something that is different about them to associate them with different PendingIntents. This may be any of the Intent attributes considered by Intent#filterEquals(Intent), or different request code integers supplied to getActivity(Context, int, Intent, int), getActivities(Context, int, Intent[], int), getBroadcast(Context, int, Intent, int), or getService(Context, int, Intent, int).
Since it seems that it still isn't that clear, let me try to explain:
When you want to use a PendingIntent
object, you don't just instantiate one. Rather, you obtain one from the system using the PendingIntent
static methods (getActivity
, getBroadcast
, getService
etc). The system keeps a bunch of PendingIntent instances and gives you one. Which one it gives you, it depends on the input parameters you pass to these getter methods. Those input parameters are: Context
, i.e. the target receiver of the intent, the Intent
to use, requestCode
and flags
. When you pass the same Context
, the same requestCode
and the same Intent (meaning an intent that filterEquals
with another intent), you get the same PendingIntent
object. The point is that the system wants to have as few PendingIntent
objects as possible, so it tends to reuse the existing ones, as much as possible.
For example, you have two calendar notifications, for two different dates. When you click on one of them, you want your app to open to the corresponding date of that notification. In that scenario, you have the same Context
target, and the Intent
object you are passing differ only in the EXTRA_DATA (which specifies the date that should be open). If you provide the same requestCode
when obtaining the PendingIntent
object, then you will end up with the same PendingIntent
object. So, when creating the second notification, you will replace the old Intent
object with the new EXTRA_DATA, and end up with two notifications pointing to the same date.
If you want to have two different PendingIntent
objects, as you should in this scenario, you should specify a different requestCode
when obtaining the PendingIntent
object.