XML : passing a Stringbuilder variable to doc

I have the following method

  private void getdata(String stringfromDate,String stringtoDate ) throws IOException {  StringBuilder retVal = new StringBuilder();    URL oracle = new URL("https://xxxxxxxxxxxxxxxx" + stringfromDate +"xxxxxxxx" + stringtoDate +"" );  BufferedReader in = new BufferedReader(  new InputStreamReader(oracle.openStream()));     String newLine = "\n";   String inputLine;   while ((inputLine = in.readLine()) != null) {   //System.out.println(inputLine);   retVal.append(inputLine).append(newLine);     }     in.close();            passSting(retVal);            }    

From this i wish to pass retVal to a the method passSting(retVal) so that i can i convert the stringbuilt String to a doc to be treated like an XML doc.

I then do this:

  private void passSting(StringBuilder retVal) {  Document doc = null;  try {  doc = (Document) loadXMLFromString(retVal.toString());//pull in the XML data into a new doc    } catch (Exception ex) {  Logger.getLogger(JavaApplication63.class.getName()).log(Level.SEVERE, null, ex);  }  }    public static org.w3c.dom.Document loadXMLFromString(String xml) throws Exception{  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  DocumentBuilder builder = factory.newDocumentBuilder();  InputSource is = new InputSource(new StringReader(xml));  return builder.parse(is);  }    

However i get the following error:

  Dec 08, 2015 8:21:51 PM javaapplication63.JavaApplication63 passSting  SEVERE: null  java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DeferredDocumentImpl cannot be cast to javax.swing.text.Document      at javaapplication63.JavaApplication63.passSting(JavaApplication63.java:152)      at javaapplication63.JavaApplication63.getdata(JavaApplication63.java:143)      at javaapplication63.JavaApplication63.access$000(JavaApplication63.java:47)      at javaapplication63.JavaApplication63$1.run(JavaApplication63.java:113)      at java.util.TimerThread.mainLoop(Timer.java:555)      at java.util.TimerThread.run(Timer.java:505)    

What am i doing wrong?