添加LocaleHelper类

public class LocaleHelper{ 
private static final String SELECTED_LANGUAGE = "Locale.Helper.Selected.Language";
public static Context onAttach(Context context) {
    String lang = getPersistedData(context, Locale.getDefault().getLanguage());
    return setLocale(context, lang);
}

public static Context onAttach(Context context, String defaultLanguage) {
    String lang = getPersistedData(context, defaultLanguage);
    return setLocale(context, lang);
}

public static String getLanguage(Context context) {
    return getPersistedData(context, Locale.getDefault().getLanguage());
}
public static Context setLocale(Context context, String language) {
    persist(context, language);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        return updateResources(context, language);
    }

    return updateResourcesLegacy(context, language);
}

private static String getPersistedData(Context context, String defaultLanguage) {
    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
    return preferences.getString(SELECTED_LANGUAGE, defaultLanguage);
}

private static void persist(Context context, String language) {
    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
    SharedPreferences.Editor editor = preferences.edit();

    editor.putString(SELECTED_LANGUAGE, language);
    editor.apply();
}

@TargetApi(Build.VERSION_CODES.N)
private static Context updateResources(Context context, String language) {
    Locale locale = new Locale(language);
    Locale.setDefault(locale);

    Configuration configuration = context.getResources().getConfiguration();
    configuration.setLocale(locale);
    configuration.setLayoutDirection(locale);

    return context.createConfigurationContext(configuration);
}

@SuppressWarnings("deprecation")
private static Context updateResourcesLegacy(Context context, String language) {
    Locale locale = new Locale(language);
    Locale.setDefault(locale);

    Resources resources = context.getResources();

    Configuration configuration = resources.getConfiguration();
    configuration.locale = locale;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        configuration.setLayoutDirection(locale);
    }

    resources.updateConfiguration(configuration, resources.getDisplayMetrics());

    return context;
}
}

在活动或片段中

Context context = LocaleHelper.setLocale(this, App.getSharedPre().getLanguage());
Resource resources = context.getResources();

现在在每个文本上设置文本

TextView tv = findViewById(R.id.tv);
tv.setText(resources.getString(R.string.tv));

如果你写

android:configChanges="locale"

在每个活动中(在清单文件中)，那么不需要每次输入activity时都设置它。

只是多添了一块，把我绊倒了。

而其他的答案，比如“de”，都没问题

String lang = "de";
Locale locale = new Locale(lang); 
Locale.setDefault(locale);
Configuration config = new Configuration();
config.locale = locale;
getBaseContext().getResources().updateConfiguration(config, 
    getBaseContext().getResources().getDisplayMetrics());

上面不会工作，例如“fr_BE”地区，所以它将使用values-fr-rBE文件夹或类似的。

需要以下轻微更改工作与“fr_BE”

String lang = "fr";

//create a string for country
String country = "BE";
//use constructor with country
Locale locale = new Locale(lang, country);

Locale.setDefault(locale);
Configuration config = new Configuration();
config.locale = locale;
getBaseContext().getResources().updateConfiguration(config, 
    getBaseContext().getResources().getDisplayMetrics());

Resources.updateConfiguration()已经弃用，我已经解决了这个问题，没有创建任何自定义的ContextWrapper。

首先我创建了一个扩展函数

fun Context.setAppLocale(language: String): Context {
    val locale = Locale(language)
    Locale.setDefault(locale)
    val config = resources.configuration
    config.setLocale(locale)
    config.setLayoutDirection(locale)
    return createConfigurationContext(config)
}

然后在活动的attachBaseContext方法中，简单地用新的上下文替换上下文。

override fun attachBaseContext(newBase: Context) {
  super.attachBaseContext(ContextWrapper(newBase.setAppLocale("bn")))
}

这个功能是由谷歌为Android 13正式推出的(也有向后支持)。Android现在允许你为每个应用程序选择语言。

官方文件在这里- https://developer.android.com/guide/topics/resources/app-languages

要设置用户的首选语言，你会要求用户在语言选择器中选择一个地区，然后在系统中设置该值:

// 1. Inside an activity, in-app language picker gets an input locale "xx-YY"
// 2. App calls the API to set its locale
mContext.getSystemService(LocaleManager.class
    ).setApplicationLocales(newLocaleList(Locale.forLanguageTag("xx-YY")));
// 3. The system updates the locale and restarts the app, including any configuration updates
// 4. The app is now displayed in "xx-YY" language

要在语言选择器中显示用户当前的首选语言，你的应用程序可以从系统中获取返回的值:

// 1. App calls the API to get the preferred locale
LocaleList currentAppLocales =
    mContext.getSystemService(LocaleManager.class).getApplicationLocales();
// 2. App uses the returned LocaleList to display languages to the user

如果你想在你的应用中保持语言变化，你必须做两件事。

首先，创建一个base Activity，让你所有的Activity都从下面扩展:

public class BaseActivity extends AppCompatActivity {

    private Locale mCurrentLocale;

    @Override
    protected void onStart() {
        super.onStart();

        mCurrentLocale = getResources().getConfiguration().locale;
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Locale locale = getLocale(this);

        if (!locale.equals(mCurrentLocale)) {

            mCurrentLocale = locale;
            recreate();
        }
    }

    public static Locale getLocale(Context context){
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);

        String lang = sharedPreferences.getString("language", "en");
        switch (lang) {
            case "English":
                lang = "en";
                break;
            case "Spanish":
                lang = "es";
                break;
        }
        return new Locale(lang);
    }
}

注意，我将新语言保存在sharedPreference中。

其次，像这样创建一个应用程序的扩展:

    public class App extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        setLocale();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        setLocale();
    }

    private void setLocale() {

        final Resources resources = getResources();
        final Configuration configuration = resources.getConfiguration();
        final Locale locale = getLocale(this);
        if (!configuration.locale.equals(locale)) {
            configuration.setLocale(locale);
            resources.updateConfiguration(configuration, null);
        }
    }
}

注意，getLocale()与上面相同。

这是所有! 我希望这能帮助到一些人。