IssueTracker

Android N provides enhanced support for multilingual users, allowing them to select multiple locales in settings. In order to implement these enhancements, the resource resolution algorithm has changed with respect to locale. These changes are explained in the preview documentation's section on behavior changes at

https://developer.android.com/preview/features/multilingual-support.html



We publish an app that provides localized date/time formats. The default configuration is localized for international english. Overrides for US English are present in /values-en-rUS/ string files. Before Android N, this ensures that users with an non-US English locale see international formats. This includes both en-GB users as well as users with a custom locale such as en-DE. However, on Android N all users with an en-* locale see US English values.

Example:

res/values/strings.xml: @string/dateformat = dd-mm-yyyy
res/values-en-rUS/strings.xml: @string/dateformat = mm/dd/yyyy

Before N:
 - User with en-GB sees dd-mm-yyyy.
 - User with en-US sees mm/dd/yyyy.

On Android N:
 - Both users see mm/dd/yyyy.



A second case, with a much greater impact, concerns localization for Chinese. Nearly all zh-* locales except zh-CN use Traditional Chinese. If I write an app for the Chinese market, my default /values/ folder contains resources localized in Traditional Chinese. Overrides for Simplified are then present in the /values-zh-rCN/ folder.

This case would also break on Android N and all my users would see Simplified Chinese (values-zh-rCN) values.



The current change in the resource resolution algorithm impacts all apps that

- provide strings for their default language in res/values
- have any override for their default language with a region qualifier

It is also not possible to provide resources for the default language only in the values-xx folder (where 'xx' is the language code) since all resources must have a (fallback) value in the default configuration.



Examples:

res/values contains English strings (en)
res/values-en-rGB contains British English strings (en-GB) like "Colour"
workaround in N: duplicate all res/values resources into res/values-en


res/values contains Traditional Chinese strings (zh)
res/values-zh-rCN contains Simplified Chinese strings (zh-CN)
workaround in N: duplicate all res/values resources into res/values-zh


The main issue is that you currently cannot specify for which locale res/values/ is localized. If res/values could be configured to match a certain locale, like "en", you don't need to duplicate resources.



The attached sample project, APK and screenshots showcase the expected and actual behavior.


* Which Developer Preview (or Android Beta) build are you using? (for
       example, NPC91K). See Settings > About phone > Build number

Android N Developer Preview 3 (NPD35K)

* What device are you using? (for example, Nexus 6P)

Emulator & Nexus 9 tablet

* What are the steps to reproduce the problem? (Please provide the
minimal reproducible test case.)

1. Have a resource with override value in eu-US configuration.
2. Set locale to en-GB (done programmatically in sample).
3. Resolve resource (@string/resolved_locale in sample).

* What was the expected result?

Expected resource to resolve to value in default configuration.

* What was the actual result?

Resource resolved to value in en-US configuration.

* Relevant logcat output.

(none)