java 39 lines · 7 steps

Counting business days between two dates in Java

A static utility counts weekdays between two dates, subtracting weekday holidays, using a whole-week shortcut for speed.

Explained by highlit

Intermediate date arithmetic utility class streams recursion

1public final class BusinessDays {
2 
  private BusinessDays() {
  }
5 
  public static long between(LocalDate start, LocalDate end, Set<LocalDate> holidays) {
      if (start.isAfter(end)) {
          return -between(end, start, holidays);
      }
10 
      long totalDays = ChronoUnit.DAYS.between(start, end);
      long fullWeeks = totalDays / 7;
      long businessDays = fullWeeks * 5;
14 
      LocalDate cursor = start.plusDays(fullWeeks * 7);
      while (cursor.isBefore(end)) {
          if (!isWeekend(cursor)) {
              businessDays++;
          }
          cursor = cursor.plusDays(1);
      }
22 
      long holidayCount = holidays.stream()
              .filter(h -> !h.isBefore(start) && h.isBefore(end))
              .filter(h -> !isWeekend(h))
              .count();
27 
      return businessDays - holidayCount;
  }
30 
  public static long between(LocalDate start, LocalDate end) {
      return between(start, end, Collections.emptySet());
  }
34 
  private static boolean isWeekend(LocalDate date) {
      DayOfWeek day = date.getDayOfWeek();
      return day == DayOfWeek.SATURDAY || day == DayOfWeek.SUNDAY;
  }
39}

01 / 01

STEP 01

Walkthrough

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Three takeaways

1Decomposing a range into full weeks plus a remainder avoids iterating every single day.
2Handling the reversed-argument case by recursing with a negated result keeps the core logic one-directional.
3A private constructor signals a class meant only for static helper methods.

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