  @Test
  public void testCharUtilsIsHex() {

    char[] arr = { 'a', 'A', '0', '9' };
    for (char a : arr) {
      Assert.assertTrue(CharUtils.isHex(a));
    }

    char[] arr2 = { '~', ';', 'Z', 'g' };
    for (char a : arr2) {
      Assert.assertFalse(CharUtils.isHex(a));
    }
  }