How to increment time by 1 hour

Question

I have two time values. one for the previous login time and one for the current login time. I have to increase previous time login by one hour. I have used the date format

Answer 1

   Calendar calendar = Calendar.getInstance();
   calendar.setTime(previous_time);
   calendar.add(Calendar.HOUR, 1);
   previous_time = calendar.getTime();
   // do your comparison