android code for auto logout after 15 minutes of in activity

We don't provide complete code from here. You can use CountDownTimer.

CountDownTimer timer = new CountDownTimer(15 *60 * 1000, 1000) {

       public void onTick(long millisUntilFinished) {
          //Some code
       }

       public void onFinish() {
          //Logout
       }
    };

When user has stopped any action use timer.start() and when user does the action do timer.cancel().