Add business hours to Java DateTime

Question

For an issue tracking system I need to calculate the response time for a request. The timer for response time should only be running during business hours. What algorithm/library should I use for this task? (Sure thing, I know about Joda-Time or ObjectLab Kit, but couldn't find anything helping with my task. Am I missing something?)

Example:

• Business hours: 9am - 5pm (8 hours per day)
• Maximum response time: 16 hours

The method may look something like:

DateTime calculateResponseTime(DateTime issueReportedAt)

I'll give some possible inputs and results as example:

• Mon, 2011-09-19, 1:00pm -> Wed, 2011-09-21, 1:00pm
• Mon, 2011-09-19, 6:05pm -> Thu, 2011-09-22, 9:00am
• Fri, 2011-09-23, 2:00pm -> Tue, 2011-09-27, 2:00pm

Answer 1

Below code does solve the this problem

public static Date addBusinessHours(Calendar startDate, int hours, int workingHourStart, int workingHourEnd){
    System.out.println("Entering: Date Time " + startDate.getTime() + " | Remaining Hours: "+ hours + " | Working hours ("+workingHourStart+"-"+workingHourEnd+")");

    if(hours == 0){
        return startDate.getTime();
    }
    int hourOfDay = startDate.get(Calendar.HOUR_OF_DAY);
    if(startDate.get(Calendar.MINUTE) > 0){
        hourOfDay = hourOfDay +1;
    }

    int dayOfWeek = startDate.get(Calendar.DAY_OF_WEEK);

    if(dayOfWeek == Calendar.SATURDAY){
        startDate.add(Calendar.DATE, 2);
        startDate.set(Calendar.HOUR_OF_DAY, workingHourStart);
        startDate.set(Calendar.MINUTE, 0);
        startDate.set(Calendar.SECOND, 0);
        addBusinessHours(startDate, hours, workingHourStart, workingHourEnd);
    }
    if(dayOfWeek == Calendar.SUNDAY){
        startDate.add(Calendar.DATE, 1);
        startDate.set(Calendar.HOUR_OF_DAY, workingHourStart);
        startDate.set(Calendar.MINUTE, 0);
        startDate.set(Calendar.SECOND, 0);
        addBusinessHours(startDate, hours, workingHourStart, workingHourEnd);
    }

    if(dayOfWeek != Calendar.SATURDAY && dayOfWeek != Calendar.SUNDAY){
        if(hourOfDay < workingHourStart){
            startDate.set(Calendar.HOUR_OF_DAY, workingHourStart);
            startDate.set(Calendar.MINUTE, 0);
            startDate.set(Calendar.SECOND, 0);
            hourOfDay = startDate.get(Calendar.HOUR_OF_DAY);
            dayOfWeek = startDate.get(Calendar.DAY_OF_WEEK);
            addBusinessHours(startDate, hours, workingHourStart, workingHourEnd);
        }
        else if(hourOfDay >= workingHourEnd){

            startDate.add(Calendar.DATE, 1);
            startDate.set(Calendar.HOUR_OF_DAY, workingHourStart);
            startDate.set(Calendar.MINUTE, 0);
            startDate.set(Calendar.SECOND, 0);
            hourOfDay = startDate.get(Calendar.HOUR_OF_DAY);
            dayOfWeek = startDate.get(Calendar.DAY_OF_WEEK);
            addBusinessHours(startDate, hours, workingHourStart, workingHourEnd);
        }

        else if(hourOfDay >= workingHourStart && hourOfDay < workingHourEnd){
            if(hours+hourOfDay <= workingHourEnd){
                startDate.add(Calendar.HOUR_OF_DAY, hours);
                return startDate.getTime();
            }else{
                //System.out.println("¤¤" + startDate.getTime() );
                startDate.add(Calendar.DATE, 1);
                //System.out.println("¤¤" + startDate.getTime() );
                startDate.set(Calendar.HOUR_OF_DAY, workingHourStart);
                startDate.set(Calendar.MINUTE, 0);
                startDate.set(Calendar.SECOND, 0);
                //System.out.println("¤¤" + startDate.getTime() );

                System.out.println("##"+hours+ "##"+ workingHourEnd + "##" + hourOfDay);
                int remaining_hours = hours - (workingHourEnd - hourOfDay);
                addBusinessHours(startDate, remaining_hours, workingHourStart, workingHourEnd);
            }
        }
    }

    return startDate.getTime();
}

Answer 2

You need to add an extra if case to the normalization part from Anils answer because if the issue is reported on a Friday 10:00 AM and the responseHours is 10, than in the next recursive call the issueReportedAt will be Friday 10 PM, witch will be normalized to Saturday 9:00 PM, witch is invalid as well.

if (hourOfDay >= WorkingHours.TO_HOUR && dayOfWeek == Calendar.FRIDAY) {
        responseTime.add(Calendar.DATE, 3);
        responseTime.set(Calendar.HOUR_OF_DAY, WorkingHours.FROM_HOUR);
        responseTime.set(Calendar.MINUTE, WorkingHours.FROM_MINUTE);
}

Answer 3

I think what Oleg was suggesting was taking a look at the way jBPM implements this functionality for inspiration for coding your own solution. Below is my answer borrowing heavily from the source I found by doing a Google Code Search.

It does not take into account holidays, but I will leave that as an exercise for you. May I suggest using a web service to annually update a restricted date list? Good luck!

    int fromHour = 9;
int fromMinute = 0;
int toHour = 17;
int toMinute = 0;
long maxResponseTime = 16;

Date calculateResponseTime(Date issueReportedAt, long responseHours) {

    Date end = null;

    Calendar responseTime = Calendar.getInstance();
    responseTime.setTime(issueReportedAt);

    int hourOfDay = responseTime.get(Calendar.HOUR_OF_DAY);
    int dayOfWeek = responseTime.get(Calendar.DAY_OF_WEEK);

    if (hourOfDay < fromHour) {
        responseTime.set(Calendar.HOUR, fromHour);

    }

    if (hourOfDay >= toHour || dayOfWeek == 1) {
        responseTime.add(Calendar.DATE, 1);
        responseTime.set(Calendar.HOUR_OF_DAY, fromHour);
        responseTime.set(Calendar.MINUTE, fromMinute);

    } else if (dayOfWeek == 7) {
        responseTime.add(Calendar.DATE, 2);
        responseTime.set(Calendar.HOUR_OF_DAY, fromHour);
        responseTime.set(Calendar.MINUTE, fromMinute);

    }

    int hour = responseTime.get(Calendar.HOUR_OF_DAY);
    int minute = responseTime.get(Calendar.MINUTE);

    long dateMilliseconds = ((hour * 60) + minute) * 60 * 1000;
    long dayPartEndMilleseconds = ((toHour * 60) + toMinute) * 60 * 1000;
    long millisecondsInThisDayPart = dayPartEndMilleseconds
            - dateMilliseconds;

    long durationMilliseconds = responseHours * 60 * 60 * 1000;

    if (durationMilliseconds < millisecondsInThisDayPart) {
        end = new Date(responseTime.getTimeInMillis()
                + durationMilliseconds);
    } else {
        long remainder = (durationMilliseconds - millisecondsInThisDayPart) / 60 / 60 / 1000;
        Date dayPartEndDate = new Date(responseTime.getTimeInMillis()
                + durationMilliseconds);

        responseTime.setTime(dayPartEndDate);

        end = calculateResponseTime(responseTime.getTime(), remainder);
    }

    return end;

}

@Test
public void testCalculateResponseTime() {

    Calendar issueReportedAt = Calendar.getInstance();
    Calendar expectedResponseTime = Calendar.getInstance();

    issueReportedAt.set(2011, 8, 19, 13, 0, 0);
    expectedResponseTime.set(2011, 8, 21, 13, 0, 0);

    assertTrue(expectedResponseTime.getTime().equals(
            calculateResponseTime(issueReportedAt.getTime(),
                    maxResponseTime)));

    issueReportedAt.set(2011, 8, 19, 18, 5, 0);
    expectedResponseTime.set(2011, 8, 22, 9, 0, 0);

    assertTrue(expectedResponseTime.getTime().equals(
            calculateResponseTime(issueReportedAt.getTime(),
                    maxResponseTime)));

    issueReportedAt.set(2011, 8, 23, 14, 0, 0);
    expectedResponseTime.set(2011, 8, 27, 14, 0, 0);

    assertTrue(expectedResponseTime.getTime().equals(
            calculateResponseTime(issueReportedAt.getTime(),
                    maxResponseTime)));

}

Answer 4

You may take a look on the jBPM business calendar.

Another library allows you configure bank holidays but it doesn't have a notion of business hours.