JEP 314: Additional Unicode Language-Tag Extensions (original) (raw)

Owner	Naoto Sato
Type	Feature
Scope	SE
Status	Closed / Delivered
Release	10
Component	core-libs / java.util:i18n
Discussion	i18n dash dev at openjdk dot java dot net
Reviewed by	Alan Bateman, Brian Goetz
Endorsed by	Brian Goetz
Created	2017/03/24 23:19
Updated	2018/03/06 17:15
Issue	8177568

Summary

Enhance java.util.Locale and related APIs to implement additional Unicode extensions of BCP 47 language tags.

Goals

Support for BCP 47 language tags was was initially added in Java SE 7, with support for the Unicode locale extension limited to calendars and numbers. This JEP will implement more of the extensions specified in the latest LDML specification, in the relevant JDK classes.

Non-Goals

Unicode language-tag extensions other than those described below will be ignored.

Description

As of Java SE 9, the supported BCP 47 U language-tag extensions are ca and nu. This JEP will add support for the following additional extensions:

cu (currency type)
fw (first day of week)
rg (region override)
tz (time zone)

In order to support these additional extensions, changes will be made to the following APIs:

java.text.DateFormat::get*Instance will return instances based on the extensions ca, rg and/or tz
java.text.DateFormatSymbols::getInstance will return instances based on the extension rg
java.text.DecimalFormatSymbols::getInstance will return instances based on the extension rg
java.text.NumberFormat::get*Instance will return instances based on the extensions nu and/or rg
java.time.format.DateTimeFormatter::localizedBy will return DateTimeFormatter instances based on the extensions ca, rg, and/or tz
java.time.format.DateTimeFormatterBuilder::getLocalizedDateTimePattern will return pattern string based on the rg extension.
java.time.format.DecimalStyle::of will return DecimalStyle instances based on the extensions nu, and/or rg
java.time.temporal.WeekFields::of will return WeekFields instances based on the extensions fw and/or rg
java.util.Calendar::{getFirstDayOfWeek,getMinimalDaysInWeek} will return values based on the extensions fw and/or rg
java.util.Currency::getInstance will return Currency instances based on the extensions cu and/or rg
java.util.Locale::getDisplayName will return a string that includes display names for these U extensions
java.util.spi.LocaleNameProvider will have new SPIs for the keys and types of these U extensions

Risks and Assumptions

The display names returned from Locale::getDisplayName depend on the localized data provided by each locale provider.