code: public static boolean isAbsolute(String uri) {
      int i = uri.indexOf(':');
      if (i < 0)
        return false;
      while (--i >= 0) {
        switch (uri.charAt(i)) {
        case '#':
        case '/':
        case '?':
  	return false;
        }
      }
      return true;
    }
docs: Tests whether a valid URI reference is absolute. It is allowed to pass an invalid URI reference,
  but the result is not defined. It is also allowed to pass a valid URI with leading
  and trailing whitespace.
  @param uri the URI to be tested, must not be null
  @return true if the URI reference is absolute, false otherwise