@Test
 public void testIsValid() throws Exception {
   String valid = "*****@*****.**";
   String invalid = "nic@cz";
   String regex =
       "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
   assertTrue(StringValidator.isValid(valid, regex));
   assertFalse(StringValidator.isValid(invalid, regex));
 }