### Question:
StringUtil { public static boolean hasLetters(String host) { int length = host.length(); for (int i = 0; i < length; i++) { char c = host.charAt(i); if (Character.isLetter(c)) { return true; } } return false; } private  StringUtil(); static boolean hasLetters(String host);  }### Answer:
@Test public void testShouldReturnTrue() { boolean l = StringUtil.hasLetters("localhost"); Assert.assertTrue(l); l = StringUtil.hasLetters("foo.com"); Assert.assertTrue(l); }
@Test public void testShouldReturnFalse() { boolean l = StringUtil.hasLetters("123.123.123.123"); Assert.assertFalse(l); }