According to this thread on StackOverflow, “Android remembers the intent that was used to launch it”. The problem described there is exactly what I’m going through:

When the app is launched for the first time from a Notification, this can mess things up. You launch the app from a Notification and Android remembers the Intent used (from the Notification), when you later launch the app (again from a Notification), android matches the Intent in the Notification with the Intent used to launch the app for the first time, and thinks you want to bring the existing app task from the background to the foreground.

The problem: I don’t understand why Android thinks that the Intent is the same. While the activity is the same, the intent has completely different extras.

When I add flags to the intent, I’m able to fix this issue. Like for example:

Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_CLEAR_TASK

But my goal is to keep the back stack, which it doesn’t using these flags of course.

It’s a webview app with some additional screens.

The issue only exists when the app is launched through a notification. When I launch it myself and put it to the background, everything works as I wish.

Scenario

• not1 = notification with activity MainActivity and extra "openLink" = https://something.com/one
• not2 = notification with activity OtherActivity and some extras
• not3 = notification with activity MainActivity and extra "openLink" = https://something.com/two

• app is closed.

What I want:

1. user clicks on not1, app launches, opens MainActivity, opens link in webview
2. user clicks on not2, app opens OtherActivity
3. user clicks on not3, app opens MainActivity, opens link in webview
4. user clicks “back”, OtherActivity from not2 is shown
5. user clicks “back”, MainActivity from not1 is shown

How it is right now:

1. user clicks on not1, app launches, opens MainActivity, opens link in webview ✅
2. user clicks on not2, app opens OtherActivity ✅
3. user clicks on not3, app opens and shows OtherActivity. Not calling onCreate(). If the app was in background, in calls onResume() of OtherActivity. Even though it was supposed to open MainActivity.

My code:

val pendingIntent = PendingIntent.getActivity(
    baseContext,
    notificationId,
    newIntent,
    PendingIntent.FLAG_IMMUTABLE
)

notificationBuilder = notificationBuilder.setContentIntent(pendingIntent)
val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.notify(notificationId, notificationBuilder.build())

notificationId is unique. extras of newIntent are unique. I tried every flag there is I believe. MainActivity (which has the webview) has launchMode “singleTop”, but of course I tried without setting a launchMode.

Further observations:

• If I set android:taskAffinity=”” and user clicks on not3 it works, but messes up the back stack. it just pulls the MainActivity in front of the backstack.