Environment

Jetpack Compose version: BOM 2024.02.01
Jetpack Compose component used: DatePicker
Android Studio Build: Android Studio Hedgehog | 2023.1.1 Patch 2
Kotlin version: 1.9.0

Description

The DatePicker component in Jetpack Compose Material 3 does not respect the locale setting provided through DatePickerState. Despite explicitly setting a locale (e.g., Locale("hr", "HR")), the DatePicker continues to use the system's default locale as determined by LocalConfiguration.current.locales[0]. The specified locale is installed on the device.

Expected Behavior

When a locale is explicitly set in DatePickerState, the DatePicker UI should adapt to use this locale for localizing labels, captions, titles, etc. If the specified locale is not installed on the device, it should fall back to using LocalConfiguration.current.locales[0].

Current Behavior

The DatePicker ignores the explicitly set locale in DatePickerState and always uses the system's default locale. This results in the UI not being localized according to the specified locale, affecting user experience for non-default language users.

Steps to Reproduce

Install additional device input language for example Croatian/Croatia
Leave English/United State as a default system language
Implement a DatePicker composable with DatePickerState explicitly set to the Croatian locale (Locale("hr", "HR")).
Observe that the DatePicker UI elements are not localized to Croatian and instead use the system's default locale.

Code sample

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun SimpleDatePicker() {
    // Setup initial date and state
    val calendar = CalendarHelper.getLocalInstance().toStartOfDay()
    val initialDateInUtcMillis = calendar.timeInMillis.toUtcMillisFromLocal()
    val datePickerState = DatePickerState(
        initialSelectedDateMillis = initialDateInUtcMillis,
        initialDisplayedMonthMillis = initialDateInUtcMillis,
        initialDisplayMode = DisplayMode.Picker,
        locale = Locale("hr", "HR")
    )

    DatePicker(
        state = datePickerState,
        modifier = Modifier.fillMaxSize()
    )
}

Probable Cause

The DatePicker implementation seems to ignore the locale parameter in DatePickerState, defaulting to the system's default locale. This is evident in the construction of the calendarModel within the DatePicker, where defaultLocale() is always used regardless of the locale specified in the state.

Suggested Fix

Modify the DatePicker implementation to respect the locale provided in DatePickerState when creating the calendarModel, ensuring that UI elements are correctly localized.

Additional Information

While the recommended approach for managing DatePickerState is through rememberDatePickerState, it does not allow for explicit localization settings via the locale parameter. This limitation becomes apparent in use cases requiring specific locale settings that differ from the system default. Although it's possible to manually implement a rememberSaveable solution that includes the locale, providing a first-class support or clearer guidance for such scenarios within the Compose framework would enhance its usability and flexibility for developers facing similar localization requirements.