Thread: Getting date based on days past year

Take a look at Calendar in the java API. It will allow you to set a date, and from there you can add on specified times and recalculate the date.A simple example:

public static void main(String[] args){
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy,MM,dd");
		Calendar cal = sdf.getCalendar();
		cal.set(2010, Calendar.JULY, 14);
		Date date = cal.getTime();
		System.out.println(sdf.format(date));
		for ( int i = 0; i < 30; i++ ){
			cal.add(Calendar.HOUR, 24);
		}
		date = cal.getTime();
		System.out.println(sdf.format(date));
}

Ok, I was having a look at it.

So tell me if I'm correct:

Calendar cal = sdf.getCalendar();
cal.set(2010, Calendar.JULY, 14);

This sets the date selection to do calculations from.

for ( int i = 0; i < 30; i++ )
{
            cal.add(Calendar.HOUR, 24);
}

This moves the selection over 30 days.


And really thats the only relevant stuff for me right?

So instead of incrementing 30 days, if I wanted to increment 38353 days from Jan-1-1990, I would say:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy,MM,dd");
Calendar cal = sdf.getCalendar();
cal.set(1990, Calendar.JANUARY, 1);
for ( int i = 0; i < 38353; i++ )
{
            cal.add(Calendar.HOUR, 24);
}

Am I correct?

Pretty much...its not extremely elegant but it works. I've never verified this method for leap years and such, so you may want to verify this with a short test.