Thread: java question regarding lilian calender

I have a program that asks a user for a date, then I compute how many days from 10/15/1582 to now that is. I want to take that number, and create a method that turns that number into a nice looking date such as "mm/dd/yyyy."

Knowing how many days from 10/15/1582, how can I create a string that displays the date since then nicely?

This is the method that takes the date and counts the number of days since 10/15/1582:

public int lilian()
  {
    // Returns the Lilian Day Number of this date.
    // Precondition: This Date is a valid date after 10/14/1582.
    //
    // Computes the number of days between 1/1/0 and this date as if no calendar
    // reforms took place, then subtracts 578,100 so that October 15, 1582 is day 1. 
 
    final int subDays = 578100;  // number of calculated days from 1/1/0 to 10/14/1582
 
    int numDays = 0;
 
    // Add days in years.
    numDays = year * 365;
 
    // Add days in the months.
    if (month <= 2) 
      numDays = numDays + (month - 1) * 31;
    else 
      numDays = numDays + ((month - 1) * 31) - ((4 * (month-1) + 27) / 10);
 
    // Add days in the days.
    numDays = numDays + day;
 
    // Take care of leap years.
    numDays = numDays + (year / 4) - (year / 100) + (year / 400);
 
    // Handle special case of leap year but not yet leap day.
    if (month < 3) 
    {
        if ((year % 4) == 0)   numDays = numDays - 1;
        if ((year % 100) == 0) numDays = numDays + 1;
        if ((year % 400) == 0) numDays = numDays - 1;
      }
 
    // Subtract extra days up to 10/14/1582.
    numDays = numDays - subDays;
    return numDays;
  }

Look at the Calendar class. It has lots of methods for working with dates.
Also look at the DateFormat class

If you have number of days, you can just do like;
1. Divide the days into number of years, months and days.
2. Add number of years into years, months into months and days into days (Remember to split date in three different variables and while adding don't forget to handle exceptions like days can't go more than 31, months not more than 12 and etc)
Hope this will help you.
Try this and if you got any problem, come up with your code.

Originally Posted by KevinWorkman

This is certainly one way to do it, but Norm's suggestion handles all of that for you, as well as dealing with things like leap years, timezones, locales, etc.

Well, what Norm told was totally useless, as far as i know. The reason is he advised him to use the built in class and not encouraged him to write one.
Well, i know that you will say, you must use built in modules in order to avoid effot. But you can not learn unless you do effort.

@KevinWorkman: I didn't mean to be rude. I actually told what was true. Don't you think, if we have a built in function and we use it. It's really easy to use than to make one, like that, to have a clear understanding and learning too.
Anyways, i am sorry if you think, i am rude. I didn't actually mean that.
My bad.

Alright. Now Peace out KevinWorkman and Thanks for advise. I am sorry Norm.