Rewrite NorwegianDateUtil to use java.time

java.util.Date and java.util.Calendar is old now and we don't want to
use that any more.

Breaking changes:

We use ZonedDateTime in stead of Date to represent a date to check
for working days.

The list of holidays are now a NavigableSet<LocalDate> and not a Date[].

Co-authored-by: tobiasgwaaler
Co-authored-by: runeflobakk
Co-authored-by: martin-jackson
Co-authored-by: hhaga
Co-authored-by: fredrbus

Author: Eivind Bergstøl

pom.xml

@@ -125,6 +125,11 @@
       <version>2.2</version>
       <scope>test</scope>
     </dependency>
+	<dependency>
+      <groupId>uk.co.probablyfine</groupId>
+      <artifactId>java-8-matchers</artifactId>
+      <version>1.9</version>
+	</dependency>
     <dependency>
       <groupId>org.hibernate.validator</groupId>
       <artifactId>hibernate-validator</artifactId>

src/main/java/no/bekk/bekkopen/date/NorwegianDateUtil.java

@@ -26,19 +26,24 @@
  * #L%
  */
 
-import java.util.Arrays;
-import java.util.Calendar;
-import java.util.Date;
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.Month;
+import java.time.ZonedDateTime;
+import java.util.Comparator;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
+import java.util.NavigableSet;
 import java.util.Set;
+import java.util.TreeSet;
+import java.util.stream.Stream;
 
 /**
  * Utility class for Norwegian dates.
  */
 public class NorwegianDateUtil {
-	private static Map<Integer, Set<Date>> holidays;
+	
+	private static Map<Integer, NavigableSet<LocalDate>> holidays;
 
 	/**
 	 * Adds the given number of working days to the given date. A working day is
@@ -60,19 +65,14 @@ public class NorwegianDateUtil {
 	 *            The number of working days to add.
 	 * @return The new date.
 	 */
-	public static Date addWorkingDaysToDate(Date date, int days) {
-		Calendar cal = dateToCalendar(date);
-
-		for (int i = 0; i < days; i++) {
-			cal.add(Calendar.DATE, 1);
-			while (!isWorkingDay(cal)) {
-				cal.add(Calendar.DATE, 1);
-			}
-		}
-
-		return cal.getTime();
+	public static ZonedDateTime addWorkingDaysToDate(ZonedDateTime date, int days) {
+		return Stream.iterate(date, (d) -> d.plusDays(1))
+			.filter(NorwegianDateUtil::isWorkingDay)
+			.limit(days + 1)
+			.max(Comparator.naturalOrder())
+			.orElse(date);
 	}
-
+	
 	/**
 	 * Will check if the given date is a working day. That is check if the given
 	 * date is a weekend day or a national holiday.
@@ -81,8 +81,8 @@ public static Date addWorkingDaysToDate(Date date, int days) {
 	 *            The date to check.
 	 * @return true if the given date is a working day, false otherwise.
 	 */
-	public static boolean isWorkingDay(Date date) {
-		return isWorkingDay(dateToCalendar(date));
+	public static boolean isWorkingDay(ZonedDateTime date) {
+		return date.getDayOfWeek() != DayOfWeek.SATURDAY && date.getDayOfWeek() != DayOfWeek.SUNDAY && !isHoliday(date);
 	}
 
 	/**
@@ -92,214 +92,100 @@ public static boolean isWorkingDay(Date date) {
 	 *            The Date to check.
 	 * @return true if holiday, false otherwise.
 	 */
-	public static boolean isHoliday(Date date) {
-		return isHoliday(dateToCalendar(date));
+	public static boolean isHoliday(ZonedDateTime date) {
+        final Set<LocalDate> holidaySet = getHolidaySet(date.getYear());
+		return holidaySet.contains(date.toLocalDate());
 	}
-
+	
 	/**
-	 * Return a sorted array of holidays for a given year.
+	 * Return a sorted set of holidays for a given year.
 	 *
 	 * @param year
 	 *            The year to get holidays for.
-	 * @return The array of holidays, sorted by date.
+	 * @return The set of holidays, naturally sorted by date.
 	 */
-	public static Date[] getHolidays(int year) {
-		Set<Date> days = getHolidaySet(year);
-		Date[] dates = days.toArray(new Date[days.size()]);
-		Arrays.sort(dates);
-		return dates;
+	public static NavigableSet<LocalDate> getHolidays(int year) {
+		return getHolidaySet(year);
 	}
 
+	/**
+	 * Calculates easter day (sunday) by using Spencer Jones formula found here:
+	 * <a href="http://no.wikipedia.org/wiki/P%C3%A5skeformelen">Wikipedia -
+	 * Påskeformelen</a>
+	 *
+	 * @param year
+	 *            The year to calculate from.
+	 * @return The LocalDate representing easter day for the given year.
+	 */
+	private static LocalDate getEasterDay(int year) {
+		int a = year % 19;
+		int b = year / 100;
+		int c = year % 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 n = (h + l - (7 * m) + 114) / 31; // This is the month number.
+		int p = (h + l - (7 * m) + 114) % 31; // This is the date minus one.
+
+		return LocalDate.of(year, n, p + 1);
+	}
+	
 	/**
 	 * Get a set of holidays for a given year.
 	 *
 	 * @param year
 	 *            The year to get holidays for.
 	 * @return The set of dates.
 	 */
-	private static Set<Date> getHolidaySet(int year) {
+	private static NavigableSet<LocalDate> getHolidaySet(int year) {
 		if (holidays == null) {
 			holidays = new HashMap<>();
 		}
 		if (!holidays.containsKey(year)) {
-			Set<Date> yearSet = new HashSet<>();
+			NavigableSet<LocalDate> yearSet = new TreeSet<>();
 
 			// Add set holidays.
-			yearSet.add(getDate(1, Calendar.JANUARY, year));
-			yearSet.add(getDate(1, Calendar.MAY, year));
-			yearSet.add(getDate(17, Calendar.MAY, year));
-			yearSet.add(getDate(25, Calendar.DECEMBER, year));
-			yearSet.add(getDate(26, Calendar.DECEMBER, year));
+			yearSet.add(LocalDate.of(year, Month.JANUARY, 1));
+			yearSet.add(LocalDate.of(year, Month.MAY, 1));
+			yearSet.add(LocalDate.of(year, Month.MAY, 17));
+			yearSet.add(LocalDate.of(year, Month.DECEMBER, 25));
+			yearSet.add(LocalDate.of(year, Month.DECEMBER, 26));
 
 			// Add movable holidays - based on easter day.
-			Calendar easterDay = dateToCalendar(getEasterDay(year));
+			final LocalDate easterDay = getEasterDay(year);
 
 			// Sunday before easter.
-			yearSet.add(rollGetDate(easterDay, -7));
+			yearSet.add(easterDay.minusDays(7));
 
 			// Thursday before easter.
-			yearSet.add(rollGetDate(easterDay, -3));
+			yearSet.add(easterDay.minusDays(3));
 
 			// Friday before easter.
-			yearSet.add(rollGetDate(easterDay, -2));
+			yearSet.add(easterDay.minusDays(2));
 
 			// Easter day.
-			yearSet.add(easterDay.getTime());
+			yearSet.add(easterDay);
 
 			// Second easter day.
-			yearSet.add(rollGetDate(easterDay, 1));
+			yearSet.add(easterDay.plusDays(1));
 
 			// "Kristi himmelfart" day.
-			yearSet.add(rollGetDate(easterDay, 39));
+			yearSet.add(easterDay.plusDays(39));
 
 			// "Pinse" day.
-			yearSet.add(rollGetDate(easterDay, 49));
+			yearSet.add(easterDay.plusDays(49));
 
 			// Second "Pinse" day.
-			yearSet.add(rollGetDate(easterDay, 50));
+			yearSet.add(easterDay.plusDays(50));
 
 			holidays.put(year, yearSet);
 		}
 		return holidays.get(year);
 	}
-
-	/**
-	 * Will check if the given date is a working day. That is check if the given
-	 * date is a weekend day or a national holiday.
-	 *
-	 * @param cal
-	 *            The Calendar object representing the date.
-	 * @return true if the given date is a working day, false otherwise.
-	 */
-	private static boolean isWorkingDay(Calendar cal) {
-		return cal.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY && cal.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY
-				&& !isHoliday(cal);
-	}
-
-	/**
-	 * Check if given Calendar object represents a holiday.
-	 *
-	 * @param cal
-	 *            The Calendar to check.
-	 * @return true if holiday, false otherwise.
-	 */
-	private static boolean isHoliday(Calendar cal) {
-		int year = cal.get(Calendar.YEAR);
-		Set<?> yearSet = getHolidaySet(year);
-		for (Object aYearSet : yearSet) {
-			Date date = (Date) aYearSet;
-			if (checkDate(cal, dateToCalendar(date))) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	/**
-	 * Calculates easter day (sunday) by using Spencer Jones formula found here:
-	 * <a href="http://no.wikipedia.org/wiki/P%C3%A5skeformelen">Wikipedia -
-	 * Påskeformelen</a>
-	 *
-	 * @param year
-	 *            The year to calculate from.
-	 * @return The Calendar object representing easter day for the given year.
-	 */
-	private static Date getEasterDay(int year) {
-		int a = year % 19;
-		int b = year / 100;
-		int c = year % 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 n = (h + l - (7 * m) + 114) / 31; // This is the month number.
-		int p = (h + l - (7 * m) + 114) % 31; // This is the date minus one.
-
-		Calendar cal = Calendar.getInstance();
-		cal.set(Calendar.YEAR, year);
-		cal.set(Calendar.MONTH, n - 1);
-		cal.set(Calendar.DATE, p + 1);
-
-		return cal.getTime();
-	}
-
-	/**
-	 * Check if the given dates match on day and month.
-	 *
-	 * @param cal
-	 *            The Calendar representing the first date.
-	 * @param other
-	 *            The Calendar representing the second date.
-	 * @return true if they match, false otherwise.
-	 */
-	private static boolean checkDate(Calendar cal, Calendar other) {
-		return checkDate(cal, other.get(Calendar.DATE), other.get(Calendar.MONTH));
-	}
-
-	/**
-	 * Check if the given date represents the given date and month.
-	 *
-	 * @param cal
-	 *            The Calendar object representing date to check.
-	 * @param date
-	 *            The date.
-	 * @param month
-	 *            The month.
-	 * @return true if they match, false otherwise.
-	 */
-	private static boolean checkDate(Calendar cal, int date, int month) {
-		return cal.get(Calendar.DATE) == date && cal.get(Calendar.MONTH) == month;
-	}
-
-	/**
-	 * Convert the given Date object to a Calendar instance.
-	 *
-	 * @param date
-	 *            The Date object.
-	 * @return The Calendar instance.
-	 */
-	private static Calendar dateToCalendar(Date date) {
-		Calendar cal = Calendar.getInstance();
-		cal.setTime(date);
-		return cal;
-	}
-
-	/**
-	 * Add the given number of days to the calendar and convert to Date.
-	 *
-	 * @param calendar
-	 *            The calendar to add to.
-	 * @param days
-	 *            The number of days to add.
-	 * @return The date object given by the modified calendar.
-	 */
-	private static Date rollGetDate(Calendar calendar, int days) {
-		Calendar easterSunday = (Calendar) calendar.clone();
-		easterSunday.add(Calendar.DATE, days);
-		return easterSunday.getTime();
-	}
-
-	/**
-	 * Get the date for the given values.
-	 *
-	 * @param day
-	 *            The day.
-	 * @param month
-	 *            The month.
-	 * @param year
-	 *            The year.
-	 * @return The date represented by the given values.
-	 */
-	private static Date getDate(int day, int month, int year) {
-		Calendar cal = Calendar.getInstance();
-		cal.set(Calendar.YEAR, year);
-		cal.set(Calendar.MONTH, month);
-		cal.set(Calendar.DATE, day);
-		return cal.getTime();
-	}
 }