### Question:
DateValidator implements ValidationPolicy<String> { public static DateValidator instance() { return instance; } private  DateValidator(); static DateValidator instance(); @Override boolean validate(String value); DateTime parseDate(String value);  }### Answer:
@Test public void testInstance() { DateValidator ts = DateValidator.instance(); assertTrue(ts.validate("2015-01-15")); assertFalse(ts.validate("2015-01-15 11:00:15")); assertFalse(ts.validate("2015/01/15 11:10:20")); assertFalse(ts.validate("12/01/2015")); assertFalse(ts.validate("13/01/2015")); }