Comparing Timestamps in Java to get difference in days

Question

I'm retrieving two timestamps from a database (check_in and check_out). I need to compare the two to find out how many days have passed between the two timestamps. How can this be done in Java?

Solution 1

Just subtract check_out and check_in, and convert from whatever units you're in to days. Something like

//pseudo-code
diff_in_millis = Absolute Value Of ( check_out - check_in ) ;
diff_in_days = diff_in_millis / (1000  * 60 * 60 * 24);

Solution 2

Following code snippet also will give days difference

private int getDaysBetween (Timestamp start, Timestamp end)   {

      boolean negative = false;
      if (end.before(start))  {
          negative = true;
          Timestamp temp = start;
          start = end;
          end = temp;
      }

      GregorianCalendar cal = new GregorianCalendar();
      cal.setTime(start);
      cal.set(Calendar.HOUR_OF_DAY, 0);
      cal.set(Calendar.MINUTE, 0);
      cal.set(Calendar.SECOND, 0);
      cal.set(Calendar.MILLISECOND, 0);

      GregorianCalendar calEnd = new GregorianCalendar();
      calEnd.setTime(end);
      calEnd.set(Calendar.HOUR_OF_DAY, 0);
      calEnd.set(Calendar.MINUTE, 0);
      calEnd.set(Calendar.SECOND, 0);
      calEnd.set(Calendar.MILLISECOND, 0);


      if (cal.get(Calendar.YEAR) == calEnd.get(Calendar.YEAR))   {
          if (negative)
               return (calEnd.get(Calendar.DAY_OF_YEAR) - cal.get(Calendar.DAY_OF_YEAR)) * -1;
          return calEnd.get(Calendar.DAY_OF_YEAR) - cal.get(Calendar.DAY_OF_YEAR);
      }

      int days = 0;
      while (calEnd.after(cal))    {
          cal.add (Calendar.DAY_OF_YEAR, 1);
          days++;
      }
      if (negative)
          return days * -1;
      return days;
  }