public SpreadsheetDate(int serial) 
{
        if ((serial  >= SERIAL_LOWER_BOUND) && (serial < = SERIAL_UPPER_BOUND)) {
            this.serial = serial;
        }
        else {
            throw new IllegalArgumentException(
                "SpreadsheetDate: Serial must be in range 2 to 2958465.");
        }
        // the day-month-year needs to be synchronised with the serial number...
      // get the year from the serial date
      final int days = this.serial - SERIAL_LOWER_BOUND;
      // overestimated because we ignored leap days
      final int overestimatedYYYY = 1900 + (days / 365);
      final int leaps = SerialDate.leapYearCount(overestimatedYYYY);
      final int nonleapdays = days - leaps;
      // underestimated because we overestimated years
      int underestimatedYYYY = 1900 + (nonleapdays / 365);
      if (underestimatedYYYY == overestimatedYYYY) {
          this.year = underestimatedYYYY;
      }
      else {
          int ss1 = calcSerial(1, 1, underestimatedYYYY);
          while (ss1 < = this.serial) {
              underestimatedYYYY = underestimatedYYYY + 1;
              ss1 = calcSerial(1, 1, underestimatedYYYY);
          }
          this.year = underestimatedYYYY - 1;
      }
      final int ss2 = calcSerial(1, 1, this.year);
      int[] daysToEndOfPrecedingMonth 
          = AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH;
      if (isLeapYear(this.year)) {
          daysToEndOfPrecedingMonth 
              = LEAP_YEAR_AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH;
      }
      // get the month from the serial date
      int mm = 1;
      int sss = ss2 + daysToEndOfPrecedingMonth[mm] - 1;
      while (sss <  this.serial) {
          mm = mm + 1;
          sss = ss2 + daysToEndOfPrecedingMonth[mm] - 1;
      }
      this.month = mm - 1;
      // what's left is d(+1);
      this.day = this.serial - ss2 
                 - daysToEndOfPrecedingMonth[this.month] + 1;
}

Standard constructor - creates a new date object representing the specified day number (which should be in the range 2 to 2958465.

Parameters:

serial - the serial number for the day (range: 2 to 2958465).

 public SpreadsheetDate(int day,
    int month,
    int year) 
{
                                               
        if ((year  >= 1900) && (year < = 9999)) {
            this.year = year;
        }
        else {
            throw new IllegalArgumentException(
                "The 'year' argument must be in range 1900 to 9999."
            );
        }
        if ((month  >= MonthConstants.JANUARY) 
                && (month < = MonthConstants.DECEMBER)) {
            this.month = month;
        }
        else {
            throw new IllegalArgumentException(
                "The 'month' argument must be in the range 1 to 12."
            );
        }
        if ((day  >= 1) && (day < = SerialDate.lastDayOfMonth(month, year))) {
            this.day = day;
        }
        else {
            throw new IllegalArgumentException("Invalid 'day' argument.");
        }
        // the serial number needs to be synchronised with the day-month-year...
        this.serial = calcSerial(day, month, year);
}

Creates a new date instance.

Parameters:

day - the day (in the range 1 to 28/29/30/31).

month - the month (in the range 1 to 12).

year - the year (in the range 1900 to 9999).

 public int compare(SerialDate other) 
{
        return this.serial - other.toSerial();
}

Returns the difference (in days) between this date and the specified 'other' date.

 public int compareTo(Object other) 
{
        return compare((SerialDate) other);
}

Implements the method required by the Comparable interface.

 public boolean equals(Object object) 
{
        if (object instanceof SerialDate) {
            final SerialDate s = (SerialDate) object;
            return (s.toSerial() == this.toSerial());
        }
        else {
            return false;
        }
}

Tests the equality of this date with an arbitrary object.

This method will return true ONLY if the object is an instance of the SerialDate base class, and it represents the same day as this SpreadsheetDate .

 public int getDayOfMonth() 
{
        return this.day;
}

Returns the day of the month.

 public int getDayOfWeek() 
{
        return (this.serial + 6) % 7 + 1;
}

Returns a code representing the day of the week.

The codes are defined in the SerialDate class as: SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.

 public int getMonth() 
{
        return this.month;
}

Returns the month (January = 1, February = 2, March = 3).

 public int getYYYY() 
{
        return this.year;
}

Returns the year (assume a valid range of 1900 to 9999).

 public int hashCode() 
{
        return toSerial();
}

Returns a hash code for this object instance.

 public boolean isAfter(SerialDate other) 
{
        return (this.serial  > other.toSerial());
}

Returns true if this SerialDate represents the same date as the specified SerialDate.

 public boolean isBefore(SerialDate other) 
{
        return (this.serial <  other.toSerial());
}

Returns true if this SerialDate represents an earlier date compared to the specified SerialDate.

 public boolean isInRange(SerialDate d1,
    SerialDate d2) 
{
        return isInRange(d1, d2, SerialDate.INCLUDE_BOTH);
}

Returns true if this SerialDate is within the specified range (INCLUSIVE). The date order of d1 and d2 is not important.

 public boolean isInRange(SerialDate d1,
    SerialDate d2,
    int include) 
{
        final int s1 = d1.toSerial();
        final int s2 = d2.toSerial();
        final int start = Math.min(s1, s2);
        final int end = Math.max(s1, s2);
        final int s = toSerial();
        if (include == SerialDate.INCLUDE_BOTH) {
            return (s  >= start && s < = end);
        }
        else if (include == SerialDate.INCLUDE_FIRST) {
            return (s  >= start && s <  end);            
        }
        else if (include == SerialDate.INCLUDE_SECOND) {
            return (s  > start && s < = end);            
        }
        else {
            return (s  > start && s <  end);            
        }
}

Returns true if this SerialDate is within the specified range (caller specifies whether or not the end-points are included). The order of d1 and d2 is not important.

 public boolean isOn(SerialDate other) 
{
        return (this.serial == other.toSerial());
}

Returns true if this SerialDate represents the same date as the specified SerialDate.

 public boolean isOnOrAfter(SerialDate other) 
{
        return (this.serial  >= other.toSerial());
}

Returns true if this SerialDate represents the same date as the specified SerialDate.

 public boolean isOnOrBefore(SerialDate other) 
{
        return (this.serial < = other.toSerial());
}

Returns true if this SerialDate represents the same date as the specified SerialDate.

 public Date toDate() 
{
        final Calendar calendar = Calendar.getInstance();
        calendar.set(getYYYY(), getMonth() - 1, getDayOfMonth(), 0, 0, 0);
        return calendar.getTime();
}

Returns a java.util.Date equivalent to this date.

 public int toSerial() 
{
        return this.serial;
}

Returns the serial number for the date, where 1 January 1900 = 2 (this corresponds, almost, to the numbering system used in Microsoft Excel for Windows and Lotus 1-2-3).