public static boolean isAlpha(String str) {
    if (str == null) {
      return false;
    }
    int sz = str.length();
    for (int i = 0; i < sz; i++) {
      if (!Character.isLetter(str.charAt(i))) {
        return false;
      }
    }
    return true;
  }
@Test
  public void testIsAlpha() {
    assertTrue("Reported hello as non-alpha string",
        StringUtils.isAlpha("hello"));
    assertFalse("Reported hello1 as alpha string",
        StringUtils.isAlpha("hello1"));
  }