db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-4752) CheapDateFormatter returns incorrect and invalid date strings
Date Wed, 21 Jul 2010 11:43:49 GMT
CheapDateFormatter returns incorrect and invalid date strings

                 Key: DERBY-4752
                 URL: https://issues.apache.org/jira/browse/DERBY-4752
             Project: Derby
          Issue Type: Bug
          Components: Services
    Affects Versions:
            Reporter: Knut Anders Hatlen
            Priority: Minor

CheapDateFormatter has multiple problems. These are the ones I'm aware of:

1) On the boundary between non-leap years and leap years it will return first day of thirteenth
month in previous year (for instance, 2011-13-01 instead of 2012-01-01)

2) It treats all years divisible by four as leap years. Those divisible by 100 and not by
400 are not leap years. It attempts to adjust for that (see the snippet below) but it always
ends up setting leapYear=true if (year%4)==0.

		// It's a leap year if divisible by 4, unless divisible by 100,
		// unless divisible by 400.
		if ((year % 4L) == 0) {
			if ((year % 100L) == 0) {
				if ((year % 400L) == 0) {
					leapYear = true;
			leapYear = true;

3) More leap year trouble. To find out which year it is, it calculates the number of four
year periods that have elapsed since 1970-01-01. A four year period is considered 365*3+366
days. Although most four year periods are of that length, some are shorter, so we'll get one
day off starting from year 2100, two days off from year 2200, and so on.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message