Checking dates if it is in a range

Question

My Java FX app handles hours worked. I have work start and end time in 2 date fields. I succeeded in calculating the differences between 2 datesTime; but now how could I check if the result is in a night or day range???? The day begin at 6 and ends at 22h. For example someone who worked between 3Am till 11Pm. Here is below how I did to have the total number of hours worked.

public void CalculNbreJourTravaille() {
    SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyy HH:mm");

    try {
        Date ddtt = format.parse(ddt.getText());
        Date dftt = format.parse(dft.getText());
        long diff = dftt.getTime() - ddtt.getTime();
        long diffhours = diff / (60*60*1000)%24;
        long diffdays = diff/(24*60*60*1000);
        long total = diffhours + (diffdays*24);
        result.setText(total + " Hours");   
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

We have workers who can work beyond 10PM, and the pay would not be the same. If they work after 10pm, they will have a special pay. We pay at the end of the work. They could would work only 10 days or more.

Answer 1

You should use the new DateTimeFormatter class to give you a LocalDateTime object, which you can pull the hour from.

DateTimeFormatter format = DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm");
LocalDateTime localDateTimeFrom = format.parse(dateFrom.getText(), LocalDateTime::from);
LocalDateTime localDateTimeTo = format.parse(dateTo.getText(), LocalDateTime::from);

int hoursFrom = localDateTimeFrom.getHour();
int hoursTo = localDateTimeTo.getHour();

boolean workedNight = hoursFrom < 6 || hoursTo > 22;

Answer 2

You can check the LocalTime part of a LocalDateTime to have a simple check using isAfter and isBefore.

I will use those values for this example.

LocalDateTime start = LocalDateTime.of(2018, Month.APRIL, 30, 23, 0);
LocalDateTime end = LocalDateTime.of(2018, Month.MAY, 1, 5, 0);

Then define the limit for the night.

LocalTime startNight = LocalTime.of(22, 0);
LocalTime endNight = LocalTime.of(6, 0);

And simply use get the LocalTime of both date and check if they are in the range. You can get the value using toLocalTime.

if(start.toLocalTime().isAfter(startNight) &&
        end.toLocalTime().isBefore(endNight)){
    System.out.println("NIGHT TIME");
} else {
    System.out.println("DAY TIME");
}

NIGHT TIME

The output is valid since we start at 23:00 and end at 05:00.

---

Using this allow a simpler solution if you need to define a time like LocalTime.of(5,45) for 5:45

This is an example, this might need some adaptation if it is allowed to start part 22 but keep working after 6. This is just an example on how to use those methods.

Answer 3

Here’s my attempt to cover all of your requirements. I wrote the code before reading that you don’t require that summer time (DST) is taken into account, so I am using ZonedDateTime to get correct hours also across summer time transitions. For the same reason I need to iterate over each day. For each date I calculate the hours worked at night time and the hours worked at day time.

If you want to make sure that summer time is not taken into account, use LocalDateTime instead of ZonedDateTime. In this case there may also be a possible performance gain in calculating the whole work days in one lump rather than one day at a time.

The code below uses 28/03/2018 03:00 and 29/03/2018 23:30 as example start and end time. Expected total hours worked are 44.5 since one day is 24 hours and there are 20.5 hours from 03:00 to 23:30. The expected day time hours are 32 since there are 16 daytime hours each of the two days. This leaves 12.5 hours as night time. And indeed the code prints

Day 32.0 hours; night 12.5 hours

The program follows. Please fill in the correct time zone where I put America/Monterey.

static ZoneId zone = ZoneId.of("America/Monterrey");
static LocalTime dayStart = LocalTime.of(6, 0);
static LocalTime dayEnd = LocalTime.of(22, 0);
static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d/M/uuuu H:mm");

public static void main(String[] args) {

    String workStartString = "28/03/2018 03:00";
    String workEndString = "29/03/2018 23:30";
    calculateWorkingHours(workStartString, workEndString);
}

public static void calculateWorkingHours(String workStartString, String workEndString) {
    ZonedDateTime workStart
            = LocalDateTime.parse(workStartString, formatter).atZone(zone);
    ZonedDateTime workEnd
            = LocalDateTime.parse(workEndString, formatter).atZone(zone);

    if (workEnd.isBefore(workStart)) {
        throw new IllegalArgumentException("Work end must not be before work start");
    }

    LocalDate workStartDate = workStart.toLocalDate();
    LocalDate workEndDate = workEnd.toLocalDate();

    Duration workedDaytime = Duration.ZERO;
    // first calculate work at nighttime before the start date, that is, work before 06:00
    Duration workedNighttime 
            = calculateNightTime(workStartDate.minusDays(1), workStart, workEnd);

    for (LocalDate d = workStartDate; ! d.isAfter(workEndDate); d = d.plusDays(1)) {
        workedDaytime = workedDaytime.plus(calculateDayTime(d, workStart, workEnd));
        workedNighttime = workedNighttime.plus(calculateNightTime(d, workStart, workEnd));
    }

    double dayHours = workedDaytime.toMinutes() / (double) TimeUnit.HOURS.toMinutes(1);
    double nightHours = workedNighttime.toMinutes() / (double) TimeUnit.HOURS.toMinutes(1);

    System.out.println("Day " + dayHours + " hours; night " + nightHours + " hours");

}

/**
 * Calculates amount of work in daytime on d,
 * that is between 06:00 and 22:00 on d.
 * Only time that falls with in workStart to workAnd
 * and also falls within 06:00 to 22:00 on d is included.
 * 
 * @param d The date for which to calculate day work
 * @param workStart
 * @param workEnd
 * @return Amount of daytime work on the said day
 */
private static Duration calculateDayTime(LocalDate d, ZonedDateTime workStart, ZonedDateTime workEnd) {
    ZonedDateTime dayStartToday = d.atTime(dayStart).atZone(zone);
    ZonedDateTime dayEndToday = d.atTime(dayEnd).atZone(zone);
    if (workStart.isAfter(dayEndToday) || workEnd.isBefore(dayStartToday)) {
        return Duration.ZERO;
    }

    // restrict calculation to daytime on d
    if (workStart.isBefore(dayStartToday)) {
        workStart = dayStartToday;
    }
    if (workEnd.isAfter(dayEndToday)) {
        workEnd = dayEndToday;
    }

    return Duration.between(workStart, workEnd);
}

/**
 * Calculates amount of night work in the night after d,
 * that is from 22:00 on d until 06:00 the next morning.
 * 
 * @param d The date for which to calculate night work
 * @param workStart
 * @param workEnd
 * @return Amount of nighttime work in said night
 */
private static Duration calculateNightTime(LocalDate d, ZonedDateTime workStart, ZonedDateTime workEnd) {
    assert ! workEnd.isBefore(workStart);

    ZonedDateTime nightStart = d.atTime(dayEnd).atZone(zone);
    ZonedDateTime nightEnd = d.plusDays(1).atTime(dayStart).atZone(zone);

    if (workEnd.isBefore(nightStart) || workStart.isAfter(nightEnd)) {
        return Duration.ZERO;
    }

    // restrict calculation to the night after d
    if (workStart.isBefore(nightStart)) {
        workStart = nightStart;
    }
    if (workEnd.isAfter(nightEnd)) {
        workEnd = nightEnd;
    }

    return Duration.between(workStart, workEnd);
}

Answer 4

This is easier, if you use the java.time API. You simply need to check, if the dates differ or if the starting time not in the range from 6:00 to 22:00:

private static final LocalTime START_TIME = LocalTime.of(6, 0); // 06:00
private static final LocalTime END_TIME = LocalTime.of(22, 0); // 22:00
private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm");

// parse from input strings
LocalDateTime start = LocalDateTime.parse(startText, FORMATTER);
LocalDateTime end = LocalDateTime.parse(endText, FORMATTER);

boolean nightTime = 
        !start.toLocalDate().equals(end.toLocalDate())
        || start.toLocalTime().isBefore(START_TIME)
        || end.toLocalTime().isAfter(END_TIME);

// todo: change output to gui
System.out.println("night time: " + nightTime);
System.out.println("duration  : " + Duration.between(start, end).toHours());

Answer 5

Define two formatters. One Fromatter to get date with time from edittext. And other On to get 12AM of that day. Now we need Date Objects corresponding to 6AM and 11PM of the same day. We can get those by adding that much milliseconds to the 12AM Object. These added dates can be used for comparison.

SimpleDateFormat df_zero_hours = new SimpleDateFormat("dd/MM/yyy");
SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy HH:mm");

Date ddtt = format.parse(ddt.getText()); //Work Start Time
Date dftt = format.parse(dft.getText()); //Work End Time


Date dateStart = df_zero_hours.parse(ddt.getText()); //12AM of the day job started
Date dayStart = new Date();
    dayStart.setTime(dateStart.getTime()+6*60*60*1000); // Get 6AM of that day
Date dayEnd = new Date();
    dayEnd.setTime(dateStart.getTime()+22*60*60*1000); //Get 10PM of that day

//        Now check the worked hours. in Whatever way you need
boolean isBefore6AM = (dayStart.getTime()-ddtt.getTime())>0;
boolean isAfter10PM = (dftt.getTime()-dayEnd.getTime())>0;