public static boolean isBlank(final CharSequence cs) {
    int strLen;
    if (cs == null || (strLen = cs.length()) == 0) {
      return true;
    }
    for (int i = 0; i < strLen; i++) {
      if (!Character.isWhitespace(cs.charAt(i))) {
        return false;
      }
    }
    return true;
  }
@Test
  public void testIsBlank() {
    assertFalse(StringUtils.isBlank("abc"));
    assertTrue(StringUtils.isNotBlank("abc"));
    assertTrue(StringUtils.isBlank("   "));
    assertTrue(StringUtils.isBlank(null));
  }