Start Android App on same activity every time

Question

I'm working on an Android app that will show college fitness professors how their students are doing in their classes. Since this data is fairly sensitive (biometrics are shown, including weight, something many college students are self-conscious about) I don't want the data to be available to anyone who picks up the tablet. While I have a proper login screen created, complete with authentication for the database, etc. I have an issue when the home button is pressed. Since Android doesn't close a program immediately on leaving the app, it's possible to reopen it and return to where you were. I would like to force the app to return to the login screen each time (I've altered onBackPressed so you can't just return to the previous view from the login screen) so that you have to re-enter your credentials to get back into the app. However, I can't seem to do this. An answer I found on here said to use the following line:

android:clearTaskOnLaunch="true"

However, no matter what XML file I put it in, be it the Manifest or the individual Activity XMLs, it appears to do nothing. So, how do I ensure the login screen comes up each time the app is launched, regardless of whether it is starting from scratch or not?

Answer 1

I found out how to do it in my case. For any others with the same problem, try following the example here:

Android detecting if an application entered the background

Answer 2

Try to play around with onUserLeaveHint() method. If you read its documentation, it says:

Its Called as part of the activity lifecycle when an activity is about to go into the background as the result of user choice. For example, when the user presses the Home key, onUserLeaveHint() will be called, but when an incoming phone call causes the in-call Activity to be automatically brought to the foreground, onUserLeaveHint() will not be called

So, when ever you detected home button pressed, you can finish the running activity/activities. So next time user click the app, it will start from the first login screen.

Hope this helps.

Answer 3

You should override onUserLeaveHint()

@Override
protected void onUserLeaveHint() {
    // do your logic
    //finish() or start login activity  
}

Answer 4

You could set a flag when onPause() is initiated within the activity. And then when you return you could check the flag from within onResume() and then request a login from that point. This will be sure to request it each time; in a simple case of course.

Edit:

With multiple activities, you could check against a saved context to see if they are the same when you start a new activity. If the contexts differ then you can discard the context previous activities context and start a new activity.

If they are the same, then you have come back to the activity from itself (you have lowered and brought the screen back). You would have to use some form of saved state such as that to do it in this manner with multiple activities when outside the case of a simple application.