"Implementing A Locale / Language Selector" for GameDevAlgorithms.com

LanguageHelper.java

public class LanguageHelper {
    public static void updateLanguage(Context ctx) {
        String lang = PreferenceManager.getDefaultSharedPreferences(ctx).getString("locale", "");
        updateLanguage(ctx, lang);
    }

    public static void updateLanguage(Context context, int language) {
        updateLanguage(context, getLocaleById(language));
    }

    private static void updateLanguage(Context ctx, String lang) {
        PreferenceManager.getDefaultSharedPreferences(ctx).edit().putString("locale", lang).apply();
        Configuration cfg = new Configuration();
        if (!TextUtils.isEmpty(lang)) {
            cfg.locale = new Locale(lang);
        } else {
            cfg.locale = Locale.getDefault();
        }

        ctx.getResources().updateConfiguration(cfg, null);
    }

    private static String getLocaleById(int id) {
        switch (id) {
            case Constants.LANG_ENGLISH:
                return "en";
            case Constants.LANG_FRENCH:
                return "fr";
            case Constants.LANG_RUSSIAN:
                return "ru";
            case Constants.LANG_DUTCH:
                return "nl";
            case Constants.LANG_CHINESE:
                return "zh";
            case Constants.LANG_KOREAN:
                return "ko";
            case Constants.LANG_JAPANESE:
                return "ja";
            case Constants.LANG_SPANISH:
                return "es";
            case Constants.LANG_GERMAN:
                return "de";
        }
        return "";
    }

    public static int getDefaultLanguage() {
        switch (Locale.getDefault().getLanguage()) {
            case "en":
                return Constants.LANG_ENGLISH;
            case "fr":
                return Constants.LANG_FRENCH;
            case "ru":
                return Constants.LANG_RUSSIAN;
            case "nl":
                return Constants.LANG_DUTCH;
            case "zh":
                return Constants.LANG_CHINESE;
            case "ko":
                return Constants.LANG_KOREAN;
            case "ja":
                return Constants.LANG_JAPANESE;
            case "es":
                return Constants.LANG_SPANISH;
            case "de":
                return Constants.LANG_GERMAN;
        }
        return Constants.LANG_ENGLISH;
    }

MainActivity.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LanguageHelper.updateLanguage(getApplicationContext());

SettingsActivity.java

new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
                setting.setIntValue(position + 1);
                setting.save();

                LanguageHelper.updateLanguage(activity, position + 1);
                ToastHelper.showPositiveToast(parentView, ToastHelper.SHORT, parentView.getSelectedItem().toString(), true);
                onResume();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parentView) {
            }
        };