Sjekk om dato er norsk hellidag / arbeidsdag

norwegianholidaycalculator.java

/**
 * Add X working days to a LocalDateTime
 *
 * @param startingDate
 * @param workingDaysToAdd
 * @return First working day after LocalDateTime with working days added
 */
public static LocalDateTime addWorkingDays(LocalDateTime startingDate, int workingDaysToAdd) {
    int days = 0;
    int workingDays = 0;

    // Add days until we have added "workingDaysToAdd" amount of working days
    while(Math.abs(workingDaysToAdd) > workingDays) {
        if (!isNorwegianHoliday(startingDate.toLocalDate().plusDays(days)))
            workingDays++;
        if (workingDaysToAdd >= 0) days++;
        else days--;
    }

    // Make sure we don't land on a Norwegian holiday, especially when workingdaysToAdd=0
    while (isNorwegianHoliday(startingDate.toLocalDate().plusDays(days))) {
        if (workingDaysToAdd >= 0) days++;
        else days--;
    }
    LocalDateTime result = startingDate.plusDays(days);

    return result;
}

/**
 * Check if date is an official Norwegian holiday
 * @param d Date to check
 * @return
 */
public static boolean isNorwegianHoliday(LocalDate d) {
    // Lørdager (inkl. Påskeaften)
    if (DayOfWeek.SATURDAY.equals(d.getDayOfWeek())) return true;
    // Søndager (inkl. Palmesøndag, 1. påskedag, 1. pinsedag)
    if (DayOfWeek.SUNDAY.equals(d.getDayOfWeek())) return true;
    // 01.01 Første nyttårsdag
    if (d.getDayOfYear() == 1) return true;
    // 01.05 Arbeidernes dag
    if (d.getDayOfMonth() == 1 && Month.MAY.equals(d.getMonth())) return true;
    // 17.05 Grunnlovsdag
    if (d.getDayOfMonth() == 17 && Month.MAY.equals(d.getMonth())) return true;
    // 25.12 1. juledag
    if (d.getDayOfMonth() == 25 && Month.DECEMBER.equals(d.getMonth())) return true;
    // 26.12 2. juledag
    if (d.getDayOfMonth() == 26 && Month.DECEMBER.equals(d.getMonth())) return true;

    LocalDate easterSunday = getEasterSunday(d.getYear());
    // Skjærtorsdag
    if (easterSunday.minusDays(3).equals(d)) return true;
    // Langfredag
    if (easterSunday.minusDays(2).equals(d)) return true;
    // 2. påskedag
    if (easterSunday.plusDays(1).equals(d)) return true;
    // Kristi Himmelfartsdag
    if (easterSunday.plusDays(39).equals(d)) return true;
    // 2. pinsedag
    if (easterSunday.plusDays(50).equals(d)) return true;

    return false;
}

/**
 * Algorithm for calculating the date of Easter Sunday (Meeus/Jones/Butcher Gregorian algorithm)
 * Based on https://no.wikipedia.org/wiki/P%C3%A5skeformelen#Meeus/Jones/Butchers_formel_(bare_for_gregoriansk_kalender)
 *
 * @param year
 * @return LocalDate of Easter Sunday in that year
 */
public static LocalDate getEasterSunday(int year) {
    int Y = year;
    int a = Y % 19;
    int b = Y / 100;
    int c = Y % 100;
    int d = b / 4;
    int e = b % 4;
    int f = (b + 8) / 25;
    int g = (b - f + 1) / 3;
    int h = (19 * a + b - d - g + 15) % 30;
    int i = c / 4;
    int k = c % 4;
    int L = (32 + 2 * e + 2 * i - h - k) % 7;
    int m = (a + 11 * h + 22 * L) / 451;
    int month = (h + L - 7 * m + 114) / 31;
    int day = ((h + L - 7 * m + 114) % 31) + 1;
    LocalDate ld = LocalDate.of(year, month, day);
    return ld;
}