title: CountdownTimer: How to restart from a remaining time when the user goes back to the previous activity?
body: <p>I'm beginner in Android and it might be really basic question.
  I'm trying to create a <code>CountDownTimer</code> which keeps countdown between two activities. Users can go to the Activity B and go back to Activity A from Activity B.
  And I am thinking of saving the remaining time in <code>SharedPreferences</code>. What I want to know is when the user does <code>OnBackPressed</code> and save the current remaining time into <code>SharedPreferences</code> and goes back to the previous activity, how can I restart the countdown timer from the remaining time in previous activity? </p>