On Tue, 14 Mar 2023 22:16:45 GMT, Justin Lu <j...@openjdk.org> wrote:
> This PR fixes the bug which occurred when `Calendar.roll(WEEK_OF_YEAR)`
> rolled into a minimal first week with an invalid `WEEK_OF_YEAR` and
> `DAY_OF_WEEK` combo.
>
> For example, Rolling _Monday, 30 December 2019_ by 1 week produced _Monday,
> 31 December 2018_, which is incorrect. This is because `WEEK_OF_YEAR` is
> rolled from 52 to 1, and the original `DAY_OF_WEEK` is 1. However, there is
> no Monday in week 1 of 2019. This is exposed when a future method calls
> `Calendar.complete()`, which eventually calculates a `fixedDate` with the
> invalid `WEEK_OF_YEAR` and `DAY_OF_WEEK` combo.
>
> To prevent this, a check is added for rolls into week 1, which determines if
> the first week is minimal. If it is indeed minimal, then it is checked if
> `DAY_OF_WEEK` exists in that week, if not, `WEEK_OF_YEAR` must be incremented
> by one.
>
> After the fix, Rolling _Monday, 30 December 2019_ by 1 week produces _Monday,
> 7 January 2019_
Hi Justin,
Thanks for the fix. Still reviewing the changes, but here are some comments I
have noticed:
src/java.base/share/classes/java/util/GregorianCalendar.java line 1314:
> 1312: // current DAY_OF_WEEK
> 1313: if (newWeekOfYear == 1 && isInvalidWeek1()) {
> 1314: newWeekOfYear+=1;
is `+1` always correct? Does it work when the amount is negative?
src/java.base/share/classes/java/util/GregorianCalendar.java line 3030:
> 3028: }
> 3029: }
> 3030:
Are these `GregorianCalendar` specific? What about other calendars?
test/jdk/java/util/Calendar/RollToMinWeek.java line 30:
> 28: * is rolled into a minimal week 1
> 29: * @run junit RollToMinWeek
> 30: */
Have you considered adding test cases into
`test/jdk/java/util/Calendar/CalendarTestScripts`, instead of creating a
single-purpose test case?
test/jdk/java/util/Calendar/RollToMinWeek.java line 79:
> 77: return Stream.of(
> 78: // Test a variety of rolls that previously produced
> incorrect results
> 79: Arguments.of(buildCalendar(27, 11, 2020, Locale.ENGLISH),
The first day of week depends on the region, not the language. In fact, I would
prefer explicitly specifying it via a locale like `en-US-u-fw-mon`, and testing
all the weekdays.
test/jdk/java/util/Calendar/RollToMinWeek.java line 95:
> 93:
> 94: private static Calendar buildCalendar(int day, int month, int year,
> Locale locale) {
> 95: Calendar calendar = Calendar.getInstance(locale);
If the fix is `GregorianCalendar` specific, should it check the type?
-------------
PR: https://git.openjdk.org/jdk/pull/13031
