What am I doing wrong?

[Sloan Bowman]

I'm trying to use TreeWalker to simply print out each element name and I keep getting this error message.
java.lang.ClassCastException
at AccessElement.parseXML(AccessElement.java:35)
at AccessElement.main(AccessElement.java:17)
Here is the code:

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.*;
import org.w3c.dom.traversal.TreeWalker;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.DocumentTraversal;
public class AccessElement
{
    public static void main(String args[]) 
    {
if ( args.length > 0)
{
    String fileName = args[0];
    
    AccessElement obj = new AccessElement();
    obj.parseXML(fileName);
}
else
{
    System.out.println("Usage: AccessElement {filename}");
} // end if else    
    } // end main()
    public void parseXML(String fileName)
    {
try {
    DocumentBuilderFactory fac = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = fac.newDocumentBuilder();
    
    Document document = builder.parse(fileName);
 
    Element documentElement = document.getDocumentElement();
    TreeWalker walker = ((DocumentTraversal)document).createTreeWalker(
       documentElement,
       NodeFilter.SHOW_ELEMENT,
       null,
       true);
        

       

    walker.firstChild();
Node currentNode = walker.getCurrentNode();
System.out.println("Node name: " + currentNode.getNodeName());
} // end try
catch (Exception e)
{
    e.printStackTrace(System.err);
} // end catch
    } // end parseXML(String fileName)
} // end class

[Ajith Kallambella]

I haven't used TreeWalker my self, but it appears that the following casting is illegal.
((DocumentTraversal)document
document is of type Document but can you cast that to DocumentTraversal type?

[Sloan Bowman]

The sad thing about this is this is parts from an example in a Book I bought. Go Figure. Thanks for your help. I'll try to figure it out.