spreadsheetdate.java

该源代码为一些通用的程序

    /**
     * Tests the equality of this date with an arbitrary object.
     * <P>
     * This method will return true ONLY if the object is an instance of the
     * {@link SerialDate} base class, and it represents the same day as this
     * {@link SpreadsheetDate}.
     *
     * @param object  the object to compare (<code>null</code> permitted).
     *
     * @return A boolean.
     */
    public boolean equals(final Object object) {

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

    }

    /**
     * Returns a hash code for this object instance.
     * 
     * @return A hash code.
     */
    public int hashCode() {
        return toSerial();
    }

    /**
     * Returns the difference (in days) between this date and the specified 
     * 'other' date.
     *
     * @param other  the date being compared to.
     *
     * @return The difference (in days) between this date and the specified 
     *         'other' date.
     */
    public int compare(final SerialDate other) {
        return this.serial - other.toSerial();
    }

    /**
     * Implements the method required by the Comparable interface.
     * 
     * @param other  the other object (usually another SerialDate).
     * 
     * @return A negative integer, zero, or a positive integer as this object 
     *         is less than, equal to, or greater than the specified object.
     */
    public int compareTo(final Object other) {
        return compare((SerialDate) other);    
    }
    
    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return <code>true</code> if this SerialDate represents the same date as
     *         the specified SerialDate.
     */
    public boolean isOn(final SerialDate other) {
        return (this.serial == other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents an earlier date compared to
     * the specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return <code>true</code> if this SerialDate represents an earlier date
     *         compared to the specified SerialDate.
     */
    public boolean isBefore(final SerialDate other) {
        return (this.serial < other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return <code>true</code> if this SerialDate represents the same date
     *         as the specified SerialDate.
     */
    public boolean isOnOrBefore(final SerialDate other) {
        return (this.serial <= other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return <code>true</code> if this SerialDate represents the same date
     *         as the specified SerialDate.
     */
    public boolean isAfter(final SerialDate other) {
        return (this.serial > other.toSerial());
    }

    /**
     * Returns true if this SerialDate represents the same date as the
     * specified SerialDate.
     *
     * @param other  the date being compared to.
     *
     * @return <code>true</code> if this SerialDate represents the same date as
     *         the specified SerialDate.
     */
    public boolean isOnOrAfter(final SerialDate other) {
        return (this.serial >= other.toSerial());
    }

    /**
     * Returns <code>true</code> if this {@link SerialDate} is within the 
     * specified range (INCLUSIVE).  The date order of d1 and d2 is not 
     * important.
     *
     * @param d1  a boundary date for the range.
     * @param d2  the other boundary date for the range.
     *
     * @return A boolean.
     */
    public boolean isInRange(final SerialDate d1, final SerialDate d2) {
        return isInRange(d1, d2, SerialDate.INCLUDE_BOTH);
    }

    /**
     * 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.
     *
     * @param d1  one boundary date for the range.
     * @param d2  a second boundary date for the range.
     * @param include  a code that controls whether or not the start and end 
     *                 dates are included in the range.
     *
     * @return <code>true</code> if this SerialDate is within the specified 
     *         range.
     */
    public boolean isInRange(final SerialDate d1, final SerialDate d2, 
                             final 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);            
        }    
    }

    /**
     * Calculate the serial number from the day, month and year.
     * <P>
     * 1-Jan-1900 = 2.
     *
     * @param d  the day.
     * @param m  the month.
     * @param y  the year.
     *
     * @return the serial number from the day, month and year.
     */
    private int calcSerial(final int d, final int m, final int y) {
        final int yy = ((y - 1900) * 365) + SerialDate.leapYearCount(y - 1);
        int mm = SerialDate.AGGREGATE_DAYS_TO_END_OF_PRECEDING_MONTH[m];
        if (m > MonthConstants.FEBRUARY) {
            if (SerialDate.isLeapYear(y)) {
                mm = mm + 1;
            }
        }
        final int dd = d;
        return yy + mm + dd + 1;
    }

    /**
     * Calculate the day, month and year from the serial number.
     */
    private void calcDayMonthYear() {

        // 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;

    }

}