Update BusinessDaysExamples.java

Author: lokeshgupta1981

src/com/howtodoinjava/core/datetime/BusinessDaysExamples.java

@@ -7,10 +7,11 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class BusinessDaysExamples {
-	public static void main(String[] args) {
+	public static void main(final String[] args) {
 		LocalDate today = LocalDate.of(2020, 5, 5);
 
 		System.out.println(addBusinessDays(today, 8, Optional.empty()));
@@ -25,14 +26,15 @@ public static void main(String[] args) {
 		System.out.println(subtractBusinessDays(today, 8, Optional.empty()));
 		System.out.println(subtractBusinessDays(today, 8, Optional.of(holidays)));
 
-		System.out.println(countBusinessDaysBetween(today, today.plusDays(20), Optional.empty()));
-		System.out.println(countBusinessDaysBetween(today, today.plusDays(20), Optional.of(holidays)));
+		System.out.println(countBusinessDaysBetween_Java8(today, today.plusDays(20), Optional.empty()).size());
+		System.out.println(countBusinessDaysBetween_Java9(today, today.plusDays(20), Optional.of(holidays)).size());
 	}
 
-	private static LocalDate addBusinessDays(LocalDate localDate, int days, Optional<List<LocalDate>> holidays) {
+	private static LocalDate addBusinessDays(final LocalDate localDate, int days,
+			final Optional<List<LocalDate>> holidays) {
 		if (localDate == null || days <= 0) {
-			throw new IllegalArgumentException("Invalid method argument(s) " + "to addBusinessDays(" + localDate + ","
-					+ days + "," + holidays + ")");
+			throw new IllegalArgumentException(
+					"Invalid method argument(s) to addBusinessDays(" + localDate + "," + days + "," + holidays + ")");
 		}
 
 		Predicate<LocalDate> isHoliday = date -> holidays.isPresent() && holidays.get().contains(date);
@@ -50,10 +52,11 @@ private static LocalDate addBusinessDays(LocalDate localDate, int days, Optional
 		return result;
 	}
 
-	private static LocalDate subtractBusinessDays(LocalDate localDate, int days, Optional<List<LocalDate>> holidays) {
+	private static LocalDate subtractBusinessDays(final LocalDate localDate, int days,
+			final Optional<List<LocalDate>> holidays) {
 		if (localDate == null || days <= 0) {
-			throw new IllegalArgumentException("Invalid method argument(s) " + "to subtractBusinessDays(" + localDate
-					+ "," + days + "," + holidays + ")");
+			throw new IllegalArgumentException(
+					"Invalid method argument(s) to addBusinessDays(" + localDate + "," + days + "," + holidays + ")");
 		}
 
 		Predicate<LocalDate> isHoliday = date -> holidays.isPresent() && holidays.get().contains(date);
@@ -71,21 +74,59 @@ private static LocalDate subtractBusinessDays(LocalDate localDate, int days, Opt
 		return result;
 	}
 
-	private static long countBusinessDaysBetween(LocalDate startDate, LocalDate endDate,
-			Optional<List<LocalDate>> holidays) {
+	private static List<LocalDate> countBusinessDaysBetween_Java8(final LocalDate startDate, final LocalDate endDate,
+			final Optional<List<LocalDate>> holidays) {
+		// Validate method arguments
 		if (startDate == null || endDate == null) {
-			throw new IllegalArgumentException("Invalid method argument(s) to countBusinessDaysBetween(" + startDate
+			throw new IllegalArgumentException("Invalid method argument(s) to countBusinessDaysBetween (" + startDate
 					+ "," + endDate + "," + holidays + ")");
 		}
 
+		// Predicate 1 : Is a given date is holiday
 		Predicate<LocalDate> isHoliday = date -> holidays.isPresent() && holidays.get().contains(date);
 
+		// Predicate 2 : Is a given date is weekday
 		Predicate<LocalDate> isWeekend = date -> date.getDayOfWeek() == DayOfWeek.SATURDAY
 				|| date.getDayOfWeek() == DayOfWeek.SUNDAY;
 
+		// Get all days between two dates
 		long daysBetween = ChronoUnit.DAYS.between(startDate, endDate);
 
-		return Stream.iterate(startDate, date -> date.plusDays(1)).limit(daysBetween)
-				.filter(isHoliday.or(isWeekend).negate()).count();
+		// List<LocalDate> businessDays = startDate.datesUntil(endDate)
+		// .filter(isWeekend.or(isHoliday))
+		// .collect(Collectors.toList());
+
+		// Iterate over stream of all dates and check each day against any weekday or
+		// holiday
+		return Stream.iterate(startDate, date -> date.plusDays(1))
+				.limit(daysBetween)
+				.filter(isHoliday.or(isWeekend).negate())
+				.collect(Collectors.toList());
+	}
+
+	private static List<LocalDate> countBusinessDaysBetween_Java9(final LocalDate startDate, 
+			final LocalDate endDate,
+			final Optional<List<LocalDate>> holidays) {
+		// Validate method arguments
+		if (startDate == null || endDate == null) {
+			throw new IllegalArgumentException("Invalid method argument(s) to countBusinessDaysBetween (" + startDate
+					+ "," + endDate + "," + holidays + ")");
+		}
+
+		// Predicate 1 : Is a given date is holiday
+		Predicate<LocalDate> isHoliday = date -> holidays.isPresent() 
+											&& holidays.get().contains(date);
+
+		// Predicate 2 : Is a given date is weekday
+		Predicate<LocalDate> isWeekend = date -> date.getDayOfWeek() == DayOfWeek.SATURDAY
+				|| date.getDayOfWeek() == DayOfWeek.SUNDAY;
+
+		// Iterate over stream of all dates and check each day against any weekday or
+		// holiday
+		List<LocalDate> businessDays = startDate.datesUntil(endDate)
+				.filter(isWeekend.or(isHoliday).negate())
+				.collect(Collectors.toList());
+
+		return businessDays;
 	}
 }