Android N provides enhanced support for multilingual users, allowing them to select multiple locales in settings. Android N provides this capability by greatly expanding the number of locales supported and changing the way the system resolves resources. The new method of resolving resources is more robust and designed to be compatible with existing APKs, but you should take extra care to spot any unexpected behavior. For example, you should test to make sure that your app defaults to the expected language. Also, if your app supports multiple languages, you should ensure that this support works as intended. Finally, you should try to ensure that your app gracefully handles languages that you didn't explicitly design it to support.
This document starts by explaining the resource resolution strategy prior to Android N. Next, it describes Android N's improved resource-resolution strategy. Last, it explains how to take advantage of the expanded number of locales to support more multilingual users.
Prior to Android N, Android could not always successfully match app and system locales.
For example, assume that you have the following situation:
When your Java code refers to strings, the system would load strings from the default ({@code en_US}) resource file, even if the app has Spanish resources localized under {@code es_ES}. This is because when the system cannot find an exact match, it continues to look for resources by stripping the country code off the locale. Finally, if no match is found, the system falls back to the default, which is {@code en_US}.
The system would also default to {@code en_US} if the user chose a language that the app didn't support at all, like French. For example:
Table 1. Resource resolution without an exact locale match.
| User Settings | App Resources | Resource Resolution |
|---|---|---|
| fr_CH |
default (en) de_DE es_ES fr_FR it_IT |
Try fr_CH => Fail Try fr => Fail Use default (en) |
In this example, the system displays English strings without knowing whether the user can understand English. This behavior is pretty common today. Android N should substantially reduce the frequency of outcomes like this one.
Android N brings more robust resource resolution, and
finds better fallbacks automatically. However, to speed up resolution and improve
maintainability, you should store resources in the most common parent dialect.
For example, if you were storing Spanish resources in the {@code es-US} directory
before, move them into the {@code es-419} directory, which contains Latin American Spanish.
Similarly, if you have resource strings in a folder named {@code en-GB}, rename
the folder to {@code en-001} (international English), because the most common
parent for en-GB strings is {@code en-001}.
The following examples explain why these practices improve performance and
reliability of resource resolution.
With Android N, the case described in Table 1 is resolved differently:
Table 2. An improved resolution strategy for when there is no exact locale match.
| User Settings | App Resources | Resource Resolution |
|---|---|---|
|
default (en) de_DE es_ES fr_FR it_IT |
Try fr_CH => Fail Try fr => Fail Try children of fr => fr_FR Use fr_FR |
Now the user gets French resources instead of English. This example also shows why you should store French strings in {@code fr} rather than {@code fr_FR} for Android N. Here the course of action is to match the closest parent dialect, making resolution faster and more predictable.
In addition to this improved resolution logic, Android now offers more user languages to choose from. Let’s try the above example again with Italian specified as an additional user language, but without app support for French.
Table 3. Resource resolution when the app only matches the user's second-preferred locale setting.
| User Settings | App Resources | Resource Resolution |
|---|---|---|
|
default (en) de_DE es_ES it_IT |
Try fr_CH => Fail Try fr => Fail Try children of fr => Fail Try it_CH => Fail Try it => Fail Try children of it => it_IT Use it_IT |
The user still gets a language they understand, even though the app doesn’t support French.
Android N adds a new API {@code LocaleList.getDefault()} that lets apps directly query the list of languages a user has specified. This API allows you to create more sophisticated app behavior and better-optimized display of content. For example, Search can show results in multiple languages based on user’s settings. Browser apps can avoid offering to translate pages in a language the user already knows, and keyboard apps can auto-enable all appropriate layouts.
Up through Android 6.0 (API level 23), Android supported only one or two locales for many common languages (en, es, ar, fr, ru). Because there were only a few variants of each language, apps could get away with storing some numbers and dates as hard coded strings in resource files. However, with Android's broadened set of supported locales, there can be significant differences in formats for dates, times, currencies, and similar information even within a single locale. Hard-coding your formats can produce a confusing experience for end users. Therefore, when developing for Android N make sure to use formatters instead of hard coding numbers and date strings.
A prime example is Arabic, whose support Android N expands from one {@code ar_EG} to 27 Arabic locales. These locales can share most resources, but some prefer ASCII digits, while others prefer native digits. For example, when you want to create a sentence with a digit variable, such as "Choose a 4 digit pin", use formatters as shown below:
format(locale, "Choose a %d-digit PIN", 4)