[jdom-interest] XSL problem - null pointer exception

[Simon McLeish]

Can anyone help me? I'm trying to use an XSL transform in a method in an 
application I'm developing. I'm using code from the JDOM website, which 
should work (!), and my stylesheet should be valid (I can do the 
transform manually using SAXON from the command line).

TIA,
Simon

Details:

I get the following error:

javax.xml.transform.TransformerConfigurationException:
javax.xml.transform.TransformerConfigurationException:
javax.xml.transform.TransformerException: java.lang.NullPointerException
         at
org.apache.xalan.processor.TransformerFactoryImpl.newTransformer(TransformerFactoryImpl.java:764)
         at
ArchiveSearchResults.quickTransform(ArchiveSearchResults.java:546)
(plus a lot more in a similar vein)

Online searches say that this is usually caused by a problem with the
stylesheet, but I don't think this is what's happening here.

Here's the relevant code. I've changed the parameter to the StreamSource
initializer to a java.io.File instead of the filename as a String, as
that's what the docs say it should be, and added a few lines to stop
getting a compilation error because returnDoc is sometimes null.

public static Document quickTransform(Document in, File stylesheet) {
     // based on code found in the JDOMSource documentation

     // following is so that returnDoc is not null even if try fails
     ArrayList nullList = new ArrayList();
     Element startElement = new Element("HTML");
     nullList.add(startElement);
     Document returnDoc = new Document(nullList);

     // set up variables so don't get null pointer errors
     TransformerFactory transformerFactory =
TransformerFactory.newInstance();
     StreamSource stylesheetSource = new StreamSource(stylesheet);

     try {
       Transformer transformer =
transformerFactory.newTransformer(stylesheetSource);
       JDOMResult out = new JDOMResult();
       transformer.transform(new JDOMSource(in), out);
       returnDoc = out.getDocument();
     }
     catch (javax.xml.transform.TransformerException e) {
       e.printStackTrace();
     }
     return returnDoc;
   }