Unable to get android app back into foreground for API 31

Question

I need to get the app from background into foreground. I managed to make this work for versions below 31 by using this code:

public static void bringApplicationToFront(Context context)
{  
    Log.d("bringApplicationToFront");

    Intent notificationIntent = new Intent(context, SplashActivity.class);
    notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);

    PendingIntent pendingIntent = null;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.S) {
        pendingIntent = PendingIntent.getActivity
                (context, 0, notificationIntent, PendingIntent.FLAG_MUTABLE);
    }
    else {
        pendingIntent = PendingIntent.getActivity
                (context, 0, notificationIntent, PendingIntent.FLAG_ONE_SHOT);
    }

    try
    {
        pendingIntent.send();
    }
    catch (PendingIntent.CanceledException e)
    {
        e.printStackTrace();
    } 
}

SplashActivity is my root Activity. I tried this with a BroadcastReceiver and also by using background thread which runs the code with a delay.

I call this method from Application class like this:

@Override
public void onTrimMemory(int level)
{
    super.onTrimMemory(level);
    if (level == TRIM_MEMORY_UI_HIDDEN) {
        Print.e("App is background"); 
        bringApplicationToFront(); 
    }
}

How can I make this work for API 31?

Answer 1

Android has tightened up the restriction around launching an Activity from a background process (Service, BroadcastReceiver, etc.). You can read about this here: https://developer.android.com/guide/components/activities/background-starts#exceptions

Probably the only thing you can do is request SYSTEM_ALERT_WINDOW permission as a workaround. Personally I think this is a terrible hack and Android will probably close this loophole in a future version.