On 2 déc, 21:32, Chris <[email protected]> wrote:
> Hi
>
> I have a small question about GWT DateTimeFormat. I'm trying to
> display a date with the format:
>
> "yyyy G" (ie. 1AD, 100BC, 3000BC) etc.
>
> so i create my new Date and format it:
> Date d = new Date(-156805891175010L);
> new DateTimeFormat("yyyy G").format(d)
>
> Unfortunately I get 3000AD which is incorrect. I should be 3000BC.
> Looking at the date object, I can see it represented as "B.C.E.
> 3000-02-01T00:00:24.990Z" which therefore looks alright...
>
> Am I doing something wrong? Is this a bug? Can anyone thing of a work
> around?
>
> It seems the DateTimeFormat gets the year right, but it comes to the
> Era, it does some crazy comparaison, which I don't really understand:
>
> date.getYear() >= - JS_START_YEAR
>
> How is this ever supposed to work?
> So for 3000BC, I might get +1100 for Date.getYear() and yet it's in
> the BC ERA. Using the comparaison:
>
> -1100 >= -1900 so we end up with AD
For 3000BC, getYear() returns -3000 - 1900 = -4900 (verified in
Chrome, IE8, FF3.5 and Opera 10.10).
-4900 < -1900, so 'value' should be 0 in formatEra, so era should be
"BC"
(note: date.getYear() >= -JS_START_YEAR is equivalent to date.getYear
() + JS_START_YEAR >= 0, which is adjusting the date from Java's "1900
is 0" to "1900 really is 1900", but involves a bit less computations)
But it seems browsers are not very good when dealing with dates far in
the past (tested Chrome 3, FF3.5, IE8 and Opera 10.10):
- IE8's toJSON() has a leading 0 in front of the minus sign
("0-2999-01-08T00:00:24Z")
- IE8 and Opera's getYear() return -2999 instead of -4899
(fortunately, GWT uses getFullYear() which is OK in all four tested
browsers)
- Chrome and FF3.5 are unable to parse negative years from strings
(new Date(d.toString()) is an invalid date, Date.parse(d.toString())
returns null)
- Opera mistakenly ignores years before 1000 when parsing strings,
and substitutes the current year (new Date("Thu, Jan 08 -2999 00:00:24
GMT").toUTCString() returns "Thu, Jan 08 2009 00:00:24 GMT")
- IE8 uses the "B.C." annotation to denote negative years in toString
() and toUTCString(), and it will only parse years as negative if
using this notation too ("-2000" will be parsed as "2000", whereas
"2000 BC" will be parsed as "2000 B.C.")
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