Android应用按应用语言偏好修改时卡顿问题求助

将另一款应用中运行正常的语言选择器代码移植到新应用后，出现如下问题：进入可用语言列表点击选项时，应用直接冻结，无法返回或选择其他选项；退出重启应用后，语言已成功变更，但再次尝试修改语言仍会触发冻结。

通过Logcat确认语言变更逻辑已执行成功，但界面未及时刷新，日志如下：

• Storing App Locales : app-locales: en persisted successfully.
• Schedule relaunch activity: com.jeluchu.test.MainActivity

相关代码 #

AndroidManifest.xml #

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">
    <application
        ...
        android:localeConfig="@xml/locales_config"
        ...
        tools:targetApi="tiramisu">

        ...

        <service
            android:name="androidx.appcompat.app.AppLocalesMetadataHolderService"
            android:enabled="false"
            android:exported="false">
            <meta-data
                android:name="autoStoreLocales"
                android:value="true" />
        </service>
    </application>
</manifest>

res/xml/locales_config.xml #

<locale-config xmlns:android="http://schemas.android.com/apk/res/android">
    <locale android:name="en"/>
    <locale android:name="es"/>
</locale-config>

LanguageSettings.kt #

private fun getLanguageNumberByCode(languageCode: String): Int =
    languageMap.entries.find { it.value == languageCode }?.key ?: 0

fun getLanguageNumber(): Int {
    return if (Build.VERSION.SDK_INT >= 33)
        getLanguageNumberByCode(
            LocaleListCompat.getAdjustedDefault()[0]?.toLanguageTag().toString()
        )
    else getLanguage
}

@Composable
fun getLanguageDesc(language: Int = getLanguageNumber()): String = stringResource(
    when (language) {
        ENGLISH -> R.string.la_en_US
        SPANISH -> R.string.la_es
        else -> R.string.follow_system
    }
)

private const val ENGLISH = 1
private const val SPANISH = 2

val languageMap: Map<Int, String> = mapOf(
    ENGLISH to "en",
    SPANISH to "es"
)

LanguageView.kt (Compose) #

val language = rememberMutableStateOf(getLanguageNumber())

Scaffold {
    LazyColumn {
        item {
            PreferenceSingleChoiceItem(
                modifier = Modifier.background(milky),
                text = R.string.follow_system.toStringRes(),
                selected = language.value == 0,
                contentPadding = PaddingValues(horizontal = 12.dp, vertical = 18.dp)
            ) { onLanguageClick(language, 0) }
        }

        languageMap.forEach { languageData ->
            item {
                PreferenceSingleChoiceItem(
                    modifier = Modifier.background(milky),
                    text = getLanguageDesc(languageData.key),
                    selected = language.value == languageData.key,
                    contentPadding = PaddingValues(horizontal = 12.dp, vertical = 18.dp)
                ) { onLanguageClick(language, languageData.key) }
            }
        }
    }
}

点击事件与扩展函数 #

// onLanguageClick 实现
languageMap.getOrElse(PreferencesService.getLanguage) { "" }.setLanguage()
selected.value = id

// setLanguage 扩展函数
fun String.setLanguage() = AppCompatDelegate.setApplicationLocales(
    if (isEmpty()) LocaleListCompat.getEmptyLocaleList()
    else LocaleListCompat.forLanguageTags(this)
)

问题根源与修复方案 #

1. 核心问题 #

调用AppCompatDelegate.setApplicationLocales()后，系统会异步调度Activity重启以应用新语言，但当前代码存在两个关键问题：

• onLanguageClick中错误使用旧的偏好值获取语言码，而非用户点击的选项ID对应的码
• 系统重启Activity的调度延迟，导致UI线程因等待状态同步而阻塞冻结

2. 具体修复 #

（1）修正onLanguageClick逻辑

@Composable
fun onLanguageClick(selectedLanguageState: MutableState<Int>, id: Int) {
    val context = LocalContext.current
    // 获取点击选项对应的语言码
    val languageCode = languageMap.getOrDefault(id, "")
    // 设置应用语言
    languageCode.setLanguage()
    // 更新本地状态
    selectedLanguageState.value = id
    // 手动触发Activity重启，避免系统调度延迟
    (context as Activity).run {
        finish()
        startActivity(Intent(context, MainActivity::class.java))
    }
}

（2）优化Compose状态获取

使用derivedStateOf确保语言状态能响应系统语言变化：

@Composable
fun getCurrentLanguageNumber(): Int {
    return remember {
        derivedStateOf {
            if (Build.VERSION.SDK_INT >= 33) {
                getLanguageNumberByCode(
                    LocaleListCompat.getAdjustedDefault()[0]?.toLanguageTag().toString()
                )
            } else {
                PreferencesService.getLanguage
            }
        }
    }.value
}

在LanguageView中替换状态初始化：

val language by remember { derivedStateOf { getCurrentLanguageNumber() } }

（3）移除不必要的状态同步

由于Activity会重启，重启后会重新获取最新语言状态，可简化状态更新逻辑，避免UI线程阻塞。

内容的提问来源于stack exchange，提问作者Jéluchu