Escaping illegal characters

Question

Hi everyone,
I'm looking for some help on how to encode or "escape" illegal characters when writing strings (which contain the illegal characters) to XML. I'm basically creating an XML document which describes the structure of a JTree I have, but thus far, i've been using the replaceAll method to replace illegal characters in the strings with legal ones before converting to XML but i don't feel this is the best way to do it.
The first part of my export to xml method is:
public void export(DefaultMutableTreeNode rootNode) {
     try {
          textArea.append("Export: Exporting current tree... \n");
          final DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
          final Document document = builder.newDocument();
          try {
               GetTitle parser = new GetTitle();
               Reader reader = getReader(userI.getTarget().toString());
               new ParserDelegator().parse(reader, parser, true);
          catch (Exception e)     {
               System.out.println(e);
          String validRoot = docTitle.replaceAll("\\'", "_");
          final Element root = document.createElement(validRoot);
          root.setAttribute("node", "root");
The GetTitle method will simply get the title of the URL returned by userI.getTarget and store it in the docTitle variable. If there are any illegal characters in the validRoot string, then i get an error at the line:
final Element root = document.createElement(validRoot);
Could anyone suggest how i can encode any illegal characters in the validRoot string before i invoke the createElement method? Is there a parser I can use which already does this?
Any help will be much appreciated.
Thanks.

Answer 1

Correct me if I am wrong but the code:
Element foo = document.createElement("King's College");is essentially creating something corresponding to the XML <King's College></King's College> which is of course illegal characters in the XML tags
the solution that you went for:
Element foo = document.createElement("Root");
foo.setAttribute("Title", "King's College");is essentially equivalent to this XML <Root Title="King's College"></Root> which is a legal use of a tic mark, but still locates the data in the wrong place
Perhaps what you wanted was:
Element foo = document.createElement("Root");
foo.appendChild(document.createText("King's College"))which corresponds to the more natural XML <Root>King's College</Root>
By the way, I've never tried any of this and could have it all wrong. I just happened to be reading the XML tutorial and noticed their comments that the most common mistake in DOM style XML processing is to confuse the element nodes (which are just the tags) with the the data contained in the element which will always be in one or more text children of an element node.
see Document, Element, & Node in the API