Strings { public static boolean isNullOrEmpty(String string) { return string == null || string.isEmpty(); } private  Strings(); static boolean isNullOrEmpty(String string); static String join(String separator, Iterator<?> parts);  }
@Test public void testIsNullOrEmpty() throws Exception { assertTrue(Strings.isNullOrEmpty(null)); assertTrue(Strings.isNullOrEmpty("")); assertFalse(Strings.isNullOrEmpty(" ")); assertFalse(Strings.isNullOrEmpty("adsf")); }