code: private static char[] extractCodePoint(String codePoint) {
      try {
        return Character.toChars(Integer.valueOf(codePoint, 16));
      } catch (IllegalArgumentException e) {
        // This may be caused by NumberFormatException of Integer.valueOf() or
        // IllegalArgumentException of Character.toChars().
        throw new IllegalArgumentException("Invalid code point: \\u" + codePoint, e);
      }
    }
docs: Converts code points in a given string to actual characters. This method doesn't handle code
  points whose char counts are 2. In other words, this method doesn't handle U+10XXXX.