Writing to a xml file using DOM API

Question

Hi,
I try to write some elements in an existing xml file.
Document doc = null;
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
try
     builder = factory.newDocumentBuilder();
     doc = builder.parse("c:/WUTEMP/rules.xml");
     Element rules = doc.getDocumentElement();
     Element eRule = doc.createElement("rule");
     rules.appendChild(eRule);
     Element ruleSyntax = doc.createElement("rule-syntax");
     eRule.appendChild(ruleSyntax);
     ruleSyntax.appendChild(doc.createTextNode(syntax));
It runs without errors but the xml file isn't changed. Some ideas ?
Structure of xml file:
<rules>
</rules>
And executing code above must resulting in :
<rules>
<rule-syntax> </rule-syntax>
</rules>
But nothing happens with the file.

Answer 1

Code below did the trick:
Transformer xformer = TransformerFactory.newInstance().newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File("c:/WUTEMP/rules.xml"));
xformer.transform(source, result);