Is there an equivalent to http session for an android app?

Question

Is there a way to define something like a "session" for an android app?
I have an application that launches multiple activities and the user the app going from activity to activity etc.
Of course may switch to another app, take a phone call, stop using the app because he is busy so the app is in the background etc.
Is there an easy and meaningful way to define something like a single session across all these different cases? So that we can tell when a new session starts and possibly store some data for each session?

Answer 1

You can use SharedPreferences for that..

SharedPreferences wmbPreference1,wmbPreference2;    
SharedPreferences.Editor editor;

//wmbPreference1 for Shared Prefs that lasts forever
wmbPreference1 = PreferenceManager.getDefaultSharedPreferences(this);  

//wmbPreference2 for Shared Prefs that lasts only just once each time program is running
wmbPreference2 =getApplicationContext().getSharedPreferences("MYKEY",Activity.MODE_PRIVATE);

To save values

SharedPreferences.Editor editor = wmbPreference1.edit();
editor.putString("MYKEY", "12345");
editor.commit();

You can retrieve the values like

String Phonenumber = wmbPreference1.getString("MYKEY", "");

where MYKEY is the keyname by which you can identify the value..

Answer 2

Unfortunately its up to the developer to define what a 'session' is in Android. Since your activity can be backgrounded for a phone call for a minute and then return to foreground - is that part of the same session or two sessions? How about a gap of 20 minutes? You can store a timestamp but you are responsible for 'expiring' and implementing appropriate behavior.