Changing app locale sometimes doesn't change direction of layouts

Question

I'm changing locale of my app programmatically using the following method. It works fine but when I start an already existing singleTask activity using Intent.FLAG_ACTIVITY_CLEAR_TOP flag. Then application loses the layout direction but translation is correct. For example, if application language is Arabic then all views direction is changed to English locale (left-to-right). What could be the reason?

I'm calling following method in attachBaseContext of BaseActivity and Application class.

public Context createLocaleConfiguration(Context context,String language) {
   
        Locale newLocale = new Locale(language);
        Resources res = context.getResources();
        Configuration configuration = res.getConfiguration();

        if (Build.VERSION.SDK_INT == Build.VERSION_CODES.N) {
            LocaleList localeList = new LocaleList(newLocale);
            LocaleList.setDefault(localeList);
            configuration.setLocales(localeList);
            configuration.setLayoutDirection(newLocale);
            context = context.createConfigurationContext(configuration);

        } else {
            configuration.setLocale(newLocale);
            configuration.setLayoutDirection(configuration.locale);
            Locale.setDefault(newLocale);
            context = context.createConfigurationContext(configuration);
        }
        return context;
    }


@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(LocaleManager.getInstance().createLocaleConfiguration(newBase,language));
}

Any ideas would be appreciable. Thanks

Gagarin

Answer 1

I guess you should try to use some helper class like this one:

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();
    }

    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);
    }

    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;
    }
}

And than just use it in you application and base activity classes like that:

  override fun attachBaseContext(newBase: Context?) {
        super.attachBaseContext(LocaleHelper.onAttach(newBase))
    }

Urn

I've written a helper class but didn't post here complete code to not make it messy. Just posted important piece of code. Besides that code is same. – Gagarin

Do you recreate your activities after lang change? – Urn

Yes, and even if app is killed and started again it works until the scenario mentioned in question happens. – Gagarin

So do you recreate it in onNewIntent() after that scenario? – Urn

No, if I had to recreate in onNewIntent then what was the purpose of calling it this way. – Gagarin