Language locales have different calendars than country locales in 9+

[Bernd Eckenfels]

Hello,

Just wanted to mention a thing I noticed when switching from 8 to 11. I knew before that the Locale data provider has changed, and I could notice that for example in the writing style for abbreviated words in dates. However something I did not expect is, that the definition of Calemdars change as well.

Locale.GERMAN and Locale.GERMANY construct different calemdars under Java 11 with CLDR as opposed to Java 8 or Java 11 with compat. The most notably changes are when calculating calendar weeks (min days in first week) or the start of a week (Sunday vs. Monday).

I haven't seen that explicitely mentioned and I also wonder if this should be mentioned in the Locale JavaDoc that language locales and country locales might differ severely in that aspect.


GERMANY:
Calendar.minDays 4 java.util.GregorianCalendar[time=1596218932830,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=…,firstDayOfWeek=2,minimalDaysInFirstWeek=4,ERA=1,YEAR=2020,MONTH=6,WEEK_OF_YEAR=31,WEEK_OF_MONTH=5,DAY_OF_MONTH=31,DAY_OF_YEAR=213,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=1,HOUR=8,HOUR_OF_DAY=20,MINUTE=8,SECOND=52,MILLISECOND=830,ZONE_OFFSET=3600000,DST_OFFSET=3600000]
11.0.1+13-LTS de_DE 2011-01-01 2010-52

GERMAN
Calendar.minDays 1 java.util.GregorianCalendar[time=1596218932879,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=...,firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2020,MONTH=6,WEEK_OF_YEAR=31,WEEK_OF_MONTH=5,DAY_OF_MONTH=31,DAY_OF_YEAR=213,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=1,HOUR=8,HOUR_OF_DAY=20,MINUTE=8,SECOND=52,MILLISECOND=879,ZONE_OFFSET=3600000,DST_OFFSET=3600000]
11.0.1+13-LTS de    2011-01-01 2011-01

Sample code:

    Date d = new Date(1293843600000L);

    Locale l = Locale.GERMANY;

    Calendar c = Calendar.getInstance(l);
    System.out.println("Calendar.minDays "+ c.getMinimalDaysInFirstWeek() + " " + c);

    SimpleDateFormat sdf = newSimpleDateFormat("yyyy-MM-DD YYYY-ww", l);
    System.out.printf("%s %-5s %s%n", System.getProperty("java.vm.version"), l, sdf.format(d));


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