Clean Code

Listing B-1 (continued)
SerialDate.Java

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362
Appendix B: 
org.jfree.date.SerialDate
785 /**
786 * Factory method that returns an instance of some concrete subclass of 
787 * {@link SerialDate}.
788 *
789 * @param day the day (1-31).
790 * @param month the month (1-12).
791 * @param yyyy the year (in the range 1900 to 9999).
792 *
793 * @return An instance of {@link SerialDate}.
794 */
795 public static SerialDate createInstance(final int day, final int month, 
796 final int yyyy) {
797 return new SpreadsheetDate(day, month, yyyy);
798 }
799 
800 /**
801 * Factory method that returns an instance of some concrete subclass of 
802 * {@link SerialDate}.
803 *
804 * @param serial the serial number for the day (1 January 1900 = 2).
805 *
806 * @return a instance of SerialDate.
807 */
808 public static SerialDate createInstance(final int serial) {
809 return new SpreadsheetDate(serial);
810 }
811 
812 /**
813 * Factory method that returns an instance of a subclass of SerialDate.
814 *
815 * @param date A Java date object.
816 *
817 * @return a instance of SerialDate.
818 */
819 public static SerialDate createInstance(final java.util.Date date) {
820 
821 final GregorianCalendar calendar = new GregorianCalendar();
822 calendar.setTime(date);
823 return new SpreadsheetDate(calendar.get(Calendar.DATE),
824 calendar.get(Calendar.MONTH) + 1,
825 calendar.get(Calendar.YEAR));
826 
827 }
828 
829 /**
830 * Returns the serial number for the date, where 1 January 1900 = 2 (this
831 * corresponds, almost, to the numbering system used in Microsoft Excel for
832 * Windows and Lotus 1-2-3).
833 *
834 * @return the serial number for the date.
835 */
836 public abstract int toSerial();
837 
838 /**
839 * Returns a java.util.Date. Since java.util.Date has more precision than
840 * SerialDate, we need to define a convention for the 'time of day'.
841 *
842 * @return this as java.util.Date.
843 */
844 public abstract java.util.Date toDate();
845 
846 /**