Working with Strings

Removing unused strings

Android projects are localized through Pontoon, which relies on an external GitHub repository called android-l10n.

This repository automatically includes strings for all supported versions of Android projects (Nightly, Beta, Release), importing them from the respective branches (main, beta, release). That means engineers can safely remove strings rendered unused when landing code to main.

Making changes to existing strings

These are the general guidelines to follow when updating existing strings already exposed for localization:

If you are changing a string such that its meaning has changed, you must update the string ID.
If your changes are relevant only for English — for example, to correct a typographical error or to make capitalization consistent — then there is no need to update the string ID.

There is a gray area between needing a new ID or not. In some cases, it will be necessary to look at all the existing translations to determine if a new ID would be beneficial. You should always reach out to the localization team in case of doubt.

For more information, see this document explaining why new string IDs are required.

Prelanding strings

It is possible to preland strings to gain more time for localization. In these cases, make sure to provide additional context in the patch (e.g. Figma designs or screenshots), as localizers may need screenshots or designs to understand the context.

If the prelanded strings are not yet referenced by any code, also add tools:ignore="UnusedResources". Note that this is enforced through a linter. For example:

<string name="new_feature_title" tools:ignore="UnusedResources">New Feature</string>

Hard-coding strings

It’s possible to temporarily hard-code strings in English, for example if the content is being finalized or if the feature is only available in English. Android products can load arbitrary XML files from the values folder, while the localization infrastructure is set up to only look at values/strings.xml (via l10n.toml configuration files). Typically, a file called static_strings.xml can be used to hard-code English strings.

Editing localized files

Localized files live in values-$LOCALE folders (e.g. values-fr for French). They should not be edited directly, since automation will overwrite these changes every 24h (it only runs from android-l10n to the Firefox repository). If you spot errors and need to make changes, get in touch with the localization project manager in charge of Android projects.

If you’re completely removing a strings.xml file, file a follow-up bug to remove all localized files once the English file removal has landed in the android-l10n repository. The automation only syncs from android-l10n to Firefox and does not remove obsolete files.