### Question:
LocalizationUtils { public static boolean isValidLanguageTag(String tag) { try { ULocale locale = ULocale.forLanguageTag(tag); if (locale.toLanguageTag() == null) { return false; } if (locale.getExtension("x".charAt(0)) != null) { return false; } if (!locale.toLanguageTag().equalsIgnoreCase(tag)) { return false; } return true; } catch (Exception e) { return false; } } private  LocalizationUtils(); static LocalizedString getLocalizedElement(LocalizedString[] elements, String[] locales); static LocalizedString[] processElementsByLocales(LocalizedString[] elements, String[] locales); static LocalizedString[] processElementsByDefaultLocales(LocalizedString[] elements); static List<ULocale> getProcessedLocaleList(String[] locales); static boolean isValidLanguageTag(String tag);  }### Answer:
@Test public void testIsValidLanguageTag() { boolean nullValue = LocalizationUtils.isValidLanguageTag(null); assertFalse("Null value handled properly",nullValue); }