Java.lang.ClassCastException: org.apache.crimson.tree.XmlDocument

Question

Hi all,
i am new to java. I am trying to parse an xml document. the code is as follows:-
Document document = null;
DocumentBuilderFactory factory = ocumentBuilderFactory.newInstance();
try {
     DocumentBuilder builder = factory.newDocumentBuilder();
     document = builder.parse( new File(xmlFile) );
after this i am trying to traverse using treewalker :-
Element docElem = document.getDocumentElement();
               DocumentTraversal docTrav = (DocumentTraversal) document;
               TreeWalker treeWalk = docTrav.createTreeWalker(docElem, NodeFilter.SHOW_ELEMENT, new ConfigNodeFilter(), false);
          Node node = treeWalk.nextNode();
when i compile all is fine but while runnig it. i get the following error:-
java.lang.ClassCastException: org.apache.crimson.tree.XmlDocument
at - DocumentTraversal docTrav = (DocumentTraversal) document;.
my import statements are as follows:-
import java.io.File;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Vector;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.DocumentTraversal;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.TreeWalker;
import org.xml.sax.SAXException;
i am not able to understand why the error is coming.
any help will be appreciated.

Answer 1

"In DOMs which support the Traversal feature, DocumentTraversal will be implemented by the same objects that implement the Document interface. "
My guess is that the DOM parser you are using doesn't support the DocumentTraversal interface which is why you can not cast to that class.