OnCreate()
{
           ... ...
    Configuration config = getBaseContext().getResources().getConfiguration();
    config.locale = Locale.FRANCE;  // set locale to french
    getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
    setContentView(R.layout.main);
}

{   ... ...
    Configuration config = getBaseContext().getResources().getConfiguration();
    config.locale = Locale.ITALY;   // change locale to Italian
    getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
}

{
    Intent intent = getIntent();
    finish();
    startActivity(intent);
}

String lang = getSharedPreferences(PREFS_APP, 0).getString(LANGUAGE, Locale.getDefault().getLanguage());
locale = new Locale(lang);
if (locale != null) {
 newConfig.locale = locale;
 Locale.setDefault(locale);
 getBaseContext().getResources().updateConfiguration(newConfig, getBaseContext().getResources().getDisplayMetrics());
}

Configuration c = new Configuration();
Locale newLocale = new Locale(localeCode);
Locale.setDefault(newLocale);
c.locale = newLocale;
ctx.getResources().updateConfiguration(c, ctx.getResources().getDisplayMetrics());

Intent goTo = new Intent(ctx, MainActivity.class);
goTo.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
act.startActivity(goTo);