code: public static boolean isValidXMLString(String s) {
  
  		int length = s.length();
  
  		// Loop through the string by UNICODE codepoints. This is NOT equivalent
  		// to looping through the characters because some UNICODE codepoints can
  		// occupy more than one character.
  		int index = 0;
  		while (index < length) {
  			int codePoint = s.codePointAt(index);
  			if (!isValidXMLCharacter(codePoint)) {
  				return false;
  			}
  			index += Character.charCount(codePoint);
  		}
  
  		// If we get here then all of the characters have been checked and are
  		// valid. Unfortunately the usual case takes the longest to verify.
  		return true;
  	}
docs: Determine if the given string can be written to an XML file without
  encoding. This will be the case so long as the string does not contain
  illegal XML characters.
  
  @param s
  String to examine for illegal XML characters
  @return true if the String can be written to an XML file without
  encoding; false otherwise