Use a persistent notification to allow the user to return to running Android app

Question

I am developing an app with numerous Activities. I would like to create a persistent notification that (more or less) says, "AppName - Return to AppName" that will be present whenever my background services are running. Creating and disposing of the notification was no problem.

Now, the user could be on any of several screens/Activities, leave the application, then want to re-enter the app via the notification. The problem is, the notification must have an intent, which launches a predetermined Activity. I want the notification to re-enter the app in whatever Activity is at the top of the history stack.

My first attempt at an ugly workaround was to make an activity (let's call it "returnFromNotify") whose only job was to "finish" itself in it's "onCreate". The notification would open "returnFromNotify" in the scope of the applications history, which would then immediately remove itself, sending the user back to the previous history state in the application stack. This seems to work... unless the user has used "back" to completely back out of the app. Then, when they hit the notification, "returnFromNotify" loads, then finishes, sending them back out to the home screen (as there are no activities in the history stack for the app).

I considered trying to detect if there was anything in the history stack before "returnFromNotify", and if not, fire up my main Activity. I can't seem to find a way to do this, either.

Any input or suggestions for a Java/Android novice? FYI, My primary history is with script-based languages.

Answer 1

I guess there is no easy way to do this but instead of adding a counter in the mainActivity I would extend Application:

Base class for those who need to maintain global application state. You can provide your own implementation by specifying its name in your AndroidManifest.xml's tag, which will cause that class to be instantiated for you when the process for your application/package is created.

I would mantein the logic there and have a method like:

public Intent getIntentForLastActivityShown();

to be called when the notification item is clicked.

Answer 2

My first approach would be to use SharedPreferences and store a key value pair called something like lastDisplayedActivity. Then in each Activity's onResume (and possibly `onCreate') you would have a line like this:

sharedPreferences.edit().putInteger("lastDisplayedActivity", ReturnFromNotify.THIS_ACTIVITY_NAME);

In other words, you store an application-wide variable indicating which activity was last displayed. Then you just grab this variable from SharedPreferences and launch the corresponding activity.