[threeten-dev] j.u.Date/Calendrical/GregorianCalendar

[Stephen Colebourne]

On 7 December 2012 05:40, Masayoshi Okutsu <masayoshi.okutsu at oracle.com> wrote:
>> This would probably require reflection to implement, so isn't really
>> ideal.
>
> I thought it'd be a piece of cake to implement it with
> DateTimeBuilder.build(Class), but it wasn't.

I'd still like DateTimeBuilder to go away. So I wouldn't rely on that.

> I had to take a look at the
> "real documentation" to determine what fields need to be set to produce an
> instance of the given class...
>>   I think toInstant() and toZoneDateTime() cover most cases.
>
>
> But a Calendar isn't always a GregorianCalendar.

I was proposing toZoneDateTime() on GregorianCalendar only.
Stephen


> I prototyped the method. Here's a demo. :-)
>
> import java.util.*;
> import javax.time.*;
> import javax.time.chrono.*;
> import javax.time.chrono.global.*;
>
> public class To310Test {
>     public static void main(String[] args) {
>         Calendar cal = Calendar.getInstance();
>         LocalDate ld = cal.to(LocalDate.class);
>         System.out.println(cal.getTime() + " -> " + ld);
>         LocalDateTime ldt = cal.to(LocalDateTime.class);
>         System.out.println(cal.getTime() + " -> " + ldt);
>         ZoneDateTime zdt = cal.to(ZoneDateTime.class);
>         System.out.println(cal.getTime() + " -> " + zdt);
>
>         Calendar jcal =
> Calendar.getInstance(Locale.forLanguageTag("ja-JP-u-ca-japanese"));
>         @SuppressWarnings("unchecked")
>         ChronoLocalDate<JapaneseChrono> jld
>             = (ChronoLocalDate<JapaneseChrono>)
> jcal.to(JapaneseChrono.INSTANCE.dateNow().getClass());
>         System.out.println(cal.getTime() + " -> " + jld);
>         zdt = jcal.to(ZoneDateTime.class);
>         System.out.println(cal.getTime() + " -> " + zdt);
>     }
> }
>
> It's output:
>
> Fri Dec 07 14:25:05 JST 2012 -> 2012-12-07
> Fri Dec 07 14:25:05 JST 2012 -> 2012-12-07T05:25:05.285
> Fri Dec 07 14:25:05 JST 2012 -> 2012-12-07T14:25:05.285+09:00[Asia/Tokyo]
> Fri Dec 07 14:25:05 JST 2012 -> Japanese Heisei 24-12-07
> Fri Dec 07 14:25:05 JST 2012 -> 2012-12-07T14:25:05.656+09:00[Asia/Tokyo]
>
> It's not pretty, but works with the Japanese calendar.
>
> LocalDateTime seems to ignore ZoneID in a DateTimeBuilder, but I guess it
> shouldn't.
>
> Thanks,
> Masayoshi
>