Internationalization (i18n)

The split is clear: formatting is automatic (LocaleFormats), text translation is manual (you). Knowing which is which avoids hunting for an API that doesn’t exist.

Automatic formatting — `LocaleFormats`

LocaleFormats (in dev.crossfly.util) concentrates the locale-sensitive separators and formats, and is respected by DatePicker/TimePicker/currency masks automatically:

Field	Type	Controls
`dateFormat`	`UIConstants.DateFormat`	date order (DMY/MDY/YMD)
`dateSeparator`	`char`	date separator (`/`, `-`, `.`)
`timeSeparator`	`char`	time separator (`:`)
`is24Hour`	`boolean`	12h vs 24h
`decimalSeparator`	`char`	decimal (`,` or `.`)
`thousandsSeparator`	`char`	thousands
`weekStart`	`byte`	first day of the week

LocaleFormats.decimalSeparator = ',';
LocaleFormats.thousandsSeparator = '.';
LocaleFormats.is24Hour = true;
// from here on, the currency mask and the pickers already format in the pt-BR standard

Text translation — manual

There is no built-in string catalog. Externalize your text (your own Map/enum) and swap it according to the language:

enum Idioma { PT, EN }
static Idioma idioma = Idioma.PT;
static final Map<String, Map<Idioma,String>> T = Map.of(
   "salvar", Map.of(Idioma.PT, "Salvar", Idioma.EN, "Save"),
   "cancelar", Map.of(Idioma.PT, "Cancelar", Idioma.EN, "Cancel")
);
static String t(String chave) { return T.get(chave).get(idioma); }

// usage:
new Button(t("salvar"));

Month/day names and picker labels are public fields that you reassign to localize.

Why the layout already helps

Layouts based on fraction/Relative tolerate text of different lengths across languages (“Salvar” vs. “Enregistrer”) without breaking — another gain from not using fixed widths.

Best practices

Configure LocaleFormats once at bootstrap according to the user’s locale.
Externalize all visible text from the start (retrofitting later is expensive).
Test the “widest” languages to make sure the layout accommodates them.

Common mistakes

Looking for a built-in string/R.string system — it doesn’t exist; build your own.
Hardcoding / in the date instead of using LocaleFormats.dateSeparator.