src/java.base/share/classes/java/util/Calendar.java

rev 47733 : 8176841: Additional Unicode Language-Tag Extensions
8189134: New system properties for the default Locale extensions
Reviewed-by:

@@ -56,10 +56,11 @@
 import java.util.concurrent.ConcurrentMap;
 import sun.util.BuddhistCalendar;
 import sun.util.calendar.ZoneInfo;
 import sun.util.locale.provider.CalendarDataUtility;
 import sun.util.locale.provider.LocaleProviderAdapter;
+import sun.util.locale.provider.TimeZoneNameUtility;
 import sun.util.spi.CalendarProvider;
 
 /**
  * The <code>Calendar</code> class is an abstract class that provides methods
  * for converting between a specific instant in time and a set of {@link

@@ -126,13 +127,18 @@
  *
  * <h4><a id="first_week">First Week</a></h4>
  *
  * <code>Calendar</code> defines a locale-specific seven day week using two
  * parameters: the first day of the week and the minimal days in first week
- * (from 1 to 7).  These numbers are taken from the locale resource data when a
- * <code>Calendar</code> is constructed.  They may also be specified explicitly
- * through the methods for setting their values.
+ * (from 1 to 7).  These numbers are taken from the locale resource data or the
+ * locale itself when a <code>Calendar</code> is constructed. If the designated
+ * locale contains "fw" and/or "rg" <a href="./Locale.html#def_locale_extension">
+ * Unicode extensions</a>, the first day of the week will be obtained according to
+ * those extensions. If both "fw" and "rg" are specified, the value from "fw"
+ * extension supersedes the implicit one from "rg" extension.
+ * They may also be specified explicitly through the methods for setting their
+ * values.
  *
  * <p>When setting or getting the <code>WEEK_OF_MONTH</code> or
  * <code>WEEK_OF_YEAR</code> fields, <code>Calendar</code> must determine the
  * first week of the month or year as a reference point.  The first week of a
  * month or year is defined as the earliest seven day period beginning on

@@ -1461,11 +1467,11 @@
         public Calendar build() {
             if (locale == null) {
                 locale = Locale.getDefault();
             }
             if (zone == null) {
-                zone = TimeZone.getDefault();
+                zone = defaultTimeZone(locale);
             }
             Calendar cal;
             if (type == null) {
                 type = locale.getUnicodeLocaleType("ca");
             }

@@ -1608,11 +1614,12 @@
      *
      * @return a Calendar.
      */
     public static Calendar getInstance()
     {
-        return createCalendar(TimeZone.getDefault(), Locale.getDefault(Locale.Category.FORMAT));
+        Locale aLocale = Locale.getDefault(Locale.Category.FORMAT);
+        return createCalendar(defaultTimeZone(aLocale), aLocale);
     }
 
     /**
      * Gets a calendar using the specified time zone and default locale.
      * The <code>Calendar</code> returned is based on the current time

@@ -1635,11 +1642,11 @@
      * @param aLocale the locale for the week data
      * @return a Calendar.
      */
     public static Calendar getInstance(Locale aLocale)
     {
-        return createCalendar(TimeZone.getDefault(), aLocale);
+        return createCalendar(defaultTimeZone(aLocale), aLocale);
     }
 
     /**
      * Gets a calendar with the specified time zone and locale.
      * The <code>Calendar</code> returned is based on the current time

@@ -1653,10 +1660,20 @@
                                        Locale aLocale)
     {
         return createCalendar(zone, aLocale);
     }
 
+    private static TimeZone defaultTimeZone(Locale l) {
+        TimeZone defaultTZ = TimeZone.getDefault();
+        String shortTZID = l.getUnicodeLocaleType("tz");
+        return shortTZID != null ? 
+            TimeZoneNameUtility.convertLDMLShortID(shortTZID)
+                .map(TimeZone::getTimeZone)
+                .orElse(defaultTZ) :
+            defaultTZ;
+    }
+
     private static Calendar createCalendar(TimeZone zone,
                                            Locale aLocale)
     {
         CalendarProvider provider =
             LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale)