XML file error

Question

HI im writing elements to an xml file created from scratch.
here is the pertinent code that creates the structure
//First i create the root element
public void addRootNodeToDocument(Document doc, String componentName) {
try {
     rootElement = doc.createElement(componentName);
}catch...then these few lines of code are called repeatedly to add a child onto a parent.
I get the parent node from a map, and add a child element onto it.
Element parentElement = (Element) elementMap.get(parentString);
Element childElement = doc.createElement(componentName);
parentElement.appendChild(childElement);then i call these few lines of code to write to the xml file:
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
//transform the DOM tree to output XML file.
transformer.transform(new DOMSource(doc), new StreamResult(new FileOutputStream("testfile.xml")));when i try to open the xml file i get this error
XML document must have a top level element. Error processing resource and all thats been written to the xml file is:
<?xml version="1.0" encoding="UTF-8"?>has anyone any idea why this is occuring?
many thanks.

Answer 1

rootElement = doc.createElement(componentName);
doesn't actually set the root element, you need to do
doc.appendChild(rootElement);
afterwards