Implementing a Day Class

• Straightforward implementation:
  

  private int year
  private int month
  private int date
  

• addDays/daysFrom tedious to implement
  • April, June, September, November have 30 days
  • February has 28 days, except in leap years it has 29 days
  • All other months have 31 days
  • Leap years are divisible by 4, except after 1582, years divisible by 100 but not 400 are not leap years
  • There is no year 0; year 1 is preceded by year -1
  • In the switchover to the Gregorian calendar, ten days were dropped: October 15, 1582 is preceded by October 4