Calculating Time - HELP

[Naadir Peterson]

I need to calculate a new date using an hour value eg:
Date : 23 March 2005 14:00 pm
Hours to be added: 12
Working hours : 8am - 5 pm

I need to calculate a new date/time using the working hours, so that the added time falls within those working hours.

Thanx...

[Jonas Isberg]

Which result do you want from your calculation? Let's start with some code
that just add 12 hours to a the given date.

import java.util.Calendar;
import java.util.GregorianCalendar;
public class DateAdd {
    public static void main(String[] args) {
        Calendar calendar = new GregorianCalendar(2005, 2, 23, 14, 0);
        System.out.println(calendar.getTime());
        calendar.add(Calendar.HOUR, 12);
        System.out.println(calendar.getTime());
    }
}

On my machine this code outputs:
Wed Mar 23 14:00:00 CET 2005
Thu Mar 24 02:00:00 CET 2005

This is obviously not in your required time span. If the code above doesn't
help you solve your problem, maybe you could show some exxamples of how the
calculation should work.

[Horatio Westock]

Have a look at Calendar. You should be able to work out what methods you need to use.

[Naadir Peterson]

I've been through the Calendar class, Basically it's easy to just add time to a given date. I need to be able to calculate - say - 12 hours from a given date to incorporate the buisiness hours. If the buisiness' hours are from 8am - 5pm, and 12 hours have to be added from, say 2pm, normally the result would be 2am the following morning, but, the buissiness won't be open then. So 12 working hours from 2pm should be 5pm the following day OR 8am the day after that. I also have to incorporate weekends and public holidays, if the buisiness is closed over these periods.

Hope you'll be able to help me with this.

Cheers...

[Horatio Westock]

OK, I understand what you are trying to achieve now. I'm a bit busy, but how about the following (rough!) pseudo-code:

getEndTime( start time, number of hours )
{
  // get the amount of time left in the day
  left today = end of business day - current time
 
  // work out how much time rolls over after today
  remaining = number of hours - left today
 
  // if the amount remaining doesnt roll on to tomorrow, return now + number hours
  if( remaining <=0 )
    return now + number of hours
 
  // advance the calendar to tomorrow
  day = day + 1
 
  // skip days until we get to the next working day
  while( day == weekend or day == holiday )
    day = day + 1
 
  // now recurse with the start of the new day and the remaining time
  return getEndTime( start_of_day, remaining )
}

[ March 23, 2005: Message edited by: Horatio Westock ]