Change locale (language) inside the app in the Settings app

I want the user to be able to change the language of the application (strings are in folders like strings-de / strings.xml or strings-zh / strings.xml). It works fine when I change my phone settings to Chinese or whatever, but I'm trying the following: I have a MainActivity with multiple fragments, and in my action bar, I have a settings icon, when the user clicks on it, the Activity parameter opens, and I have a menu item where the user can select their preferred language. When the user clicks on it, the application should reload and use my strings from the selected language. How can I achieve this? and in what activity does this code belong? thank you in advance.

here's my settingsActivity:

public class SettingsActivity extends PreferenceActivity {
    private static final boolean ALWAYS_SIMPLE_PREFS = false;

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);

        setupSimplePreferencesScreen();
    }

    @SuppressWarnings("deprecation")
    private void setupSimplePreferencesScreen() {
        if (!isSimplePreferences(this)) {
            return;
        }

        // In the simplified UI, fragments are not used at all and we instead
        // use the older PreferenceActivity APIs.

        // Add 'general' preferences.
        addPreferencesFromResource(R.xml.pref_general);

        // Add 'Cash-Game Ticker' preferences, and a corresponding header.
        PreferenceCategory fakeHeader = new PreferenceCategory(this);
        fakeHeader.setTitle(R.string.pref_header_cg_notifications);
        getPreferenceScreen().addPreference(fakeHeader);
        addPreferencesFromResource(R.xml.pref_cg_notification);

        // Add 'Tournament Ticker' preferences, and a corresponding header.
        PreferenceCategory fakeHeader2 = new PreferenceCategory(this);
        fakeHeader2.setTitle(R.string.pref_header_tm_notifications);
        getPreferenceScreen().addPreference(fakeHeader2);
        addPreferencesFromResource(R.xml.pref_tm_notification);

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences to
        // their values. When their values change, their summaries are updated
        // to reflect the new value, per the Android Design guidelines.
        bindPreferenceSummaryToValue(findPreference("location_list"));
        bindPreferenceSummaryToValue(findPreference("language_list"));
        bindPreferenceSummaryToValue(findPreference("notifications_new_cg_ringtone"));
        bindPreferenceSummaryToValue(findPreference("notifications_new_tm_ringtone"));
    }

    /** {@inheritDoc} */
    @Override
    public boolean onIsMultiPane() {
        return isXLargeTablet(this) && !isSimplePreferences(this);
    }

    private static boolean isXLargeTablet(Context context) {
        return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
    }

    private static boolean isSimplePreferences(Context context) {
        return ALWAYS_SIMPLE_PREFS
                || Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB
                || !isXLargeTablet(context);
    }

    /** {@inheritDoc} */
    @Override
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public void onBuildHeaders(List<Header> target) {
        if (!isSimplePreferences(this)) {
            loadHeadersFromResource(R.xml.pref_headers, target);
        }
    }

    /**
     * A preference value change listener that updates the preference summary
     * to reflect its new value.
     */
    private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
        @Override
        public boolean onPreferenceChange(Preference preference, Object value) {
            String stringValue = value.toString();

            if (preference instanceof ListPreference) {
                // For list preferences, look up the correct display value in
                // the preference 'entries' list.
                ListPreference listPreference = (ListPreference) preference;
                int index = listPreference.findIndexOfValue(stringValue);

                // Set the summary to reflect the new value.
                preference
                        .setSummary(index >= 0 ? listPreference.getEntries()[index]
                                : null);

            } else if (preference instanceof RingtonePreference) {
                // For ringtone preferences, look up the correct display value
                // using RingtoneManager.
                if (TextUtils.isEmpty(stringValue)) {
                    // Empty values correspond to 'silent' (no ringtone).
                    preference.setSummary(R.string.pref_ringtone_silent);

                } else {
                    Ringtone ringtone = RingtoneManager.getRingtone(
                            preference.getContext(), Uri.parse(stringValue));

                    if (ringtone == null) {
                        // Clear the summary if there was a lookup error.
                        preference.setSummary(null);
                    } else {
                        // Set the summary to reflect the new ringtone display
                        // name.
                        String name = ringtone
                                .getTitle(preference.getContext());
                        preference.setSummary(name);
                    }
                }

            } else {
                // For all other preferences, set the summary to the value's
                // simple string representation.
                preference.setSummary(stringValue);
            }
            return true;
        }
    };

    private static void bindPreferenceSummaryToValue(Preference preference) {
        // Set the listener to watch for value changes.
        preference
                .setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);

        // Trigger the listener immediately with the preference's
        // current value.
        sBindPreferenceSummaryToValueListener.onPreferenceChange(
                preference,
                PreferenceManager.getDefaultSharedPreferences(
                        preference.getContext()).getString(preference.getKey(),
                        ""));
    }

    /**
     * This fragment shows general preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class GeneralPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_general);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            bindPreferenceSummaryToValue(findPreference("example_text"));
            bindPreferenceSummaryToValue(findPreference("example_list"));
        }
    }

    /**
     * This fragment shows notification preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class NotificationPreferenceFragment extends
            PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_cg_notification);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            bindPreferenceSummaryToValue(findPreference("notifications_new_message_ringtone"));
        }
    }

    /**
     * This fragment shows data and sync preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class DataSyncPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_tm_notification);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            bindPreferenceSummaryToValue(findPreference("sync_frequency"));
        }
    }
}

      

        
        
        
      

    

here's the xml part where the user can choose the language:

<ListPreference
    android:defaultValue="en"
    android:entries="@array/pref_language_select"
    android:entryValues="@array/pref_language_values"
    android:key="language_list"
    android:negativeButtonText="@null"
    android:positiveButtonText="@null"
    android:title="@string/pref_title_language" />

      

        
        
        
      

    

and here's an array from the language select list:

<string-array name="pref_language_select">
    <item>Deutsch</item>
    <item>English</item>
    <item>中文</item>
    <item>Espanol</item>
    <item>Magyar</item>
    <item>Srpski</item>
    <item>Nederlands</item>
</string-array>
<string-array name="pref_language_values">
    <item>de</item>
    <item>en</item>
    <item>zh</item>
    <item>es</item>
    <item>mg</item>
    <item>sr</item>
    <item>nl</item>        
</string-array>

      

        
        
        
      

    

I hope someone can help me, thanks in advance!