Well, you need to start with something. You already mentioned that you were starting with the current day. From there, Calendar gives you some useful tools to determine important things, like if the current year is a leap year (in which the last day of Feb. is the 29th), etc. Calendar won't do the work for you...it will just simplify the work. There is indeed an algorithm that needs to be written to calculate the series, and that I'll leave up to you. I just thought the Calendar class might help you with some of the odd cases (i.e. leap year), finding the last day of each month dynamically, etc.