Unmarshalling a DOM node to an XML file with JAXB

Question

I'm trying to unmarshall a DOM node to an XML file using JAXB. However I keep receiving a NullPointerException. This only seems to occur when I create the DOM Node from scratch. The stack trace looks like the following:
java.lang.NullPointerException
        at com.sun.xml.bind.unmarshaller.SAXUnmarshallerHandlerImpl.startElement
(SAXUnmarshallerHandlerImpl.java:87)
        at com.sun.xml.bind.unmarshaller.DOMScanner.visit(DOMScanner.java:109)
        at com.sun.xml.bind.unmarshaller.DOMScanner.parse(DOMScanner.java:64)
        at com.sun.xml.bind.unmarshaller.UnmarshallerImpl.unmarshal(Unmarshaller
Impl.java:149)
        at Main.main(Main.java:103)(If I unmarshal an XML file into a DOM node, I can successfully marshall the DOM node out to a new XML file using JAXB without error.)
Any insight into what I am doing wrong would be greatly appreciated!
Sample code and XSD follow...
Sample Code:
import itemlistsample.*;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.Text;
public class Main
  public static void main(String[] args)
      try
          JAXBContext jc = JAXBContext.newInstance( "itemlistsample" );
          Unmarshaller u = jc.createUnmarshaller();
          * Set up DOM Node Document Object.
          DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
          dbf.setNamespaceAware(true);                   
          DocumentBuilder db = dbf.newDocumentBuilder(); 
          Document doc = db.newDocument();
          System.out.println();
          System.out.println();
          System.out.println("Create a DOM Node and unmarshall to an XML file");
          * Generate elements within DOM document
          Element itemListElt = (Element)doc.createElement("item_list");
          Element itemInfo = (Element)doc.createElement("item_info");
          Element name = (Element)doc.createElement("name");
          Element price = (Element)doc.createElement("price");
          * 3-Ring Binder @ 4.99
          name.appendChild(doc.createTextNode("3-Ring Binder"));
          itemInfo.appendChild(name);
          price.appendChild(doc.createTextNode("4.99"));
          itemInfo.appendChild(price);
          itemListElt.appendChild(itemInfo);
          * Large Paper Clips @ 1.23
          itemInfo = (Element)doc.createElement("item_info");
          name = (Element)doc.createElement("name");
          price = (Element)doc.createElement("price");
          name.appendChild(doc.createTextNode("Large Paper Clips"));
          itemInfo.appendChild(name);
          price.appendChild(doc.createTextNode("1.23"));
          itemInfo.appendChild(price);
          itemListElt.appendChild(itemInfo);
          doc.appendChild(itemListElt);
          * Display DOM document as a sanity check
          itemListElt = doc.getDocumentElement();
          System.out.println(itemListElt.getTagName());
          NodeList nl = itemListElt.getElementsByTagName("item_info");
          traverse("  ", nl.item(0));
          * Use JAXB to unmarshal the DOM document into
          * an instance of the generated JAXB class for
          * the root element.  Stack trace occurs here!
          ItemListType il = (ItemListType)u.unmarshal(doc);
          * Marshal to an XML file
          Marshaller m = jc.createMarshaller();
          m.setProperty( Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE );
          m.marshal( il, new FileOutputStream("item_new.xml") );
      catch (Exception e)
     e.printStackTrace();
  public static void traverse(String indent, Node n)
    if (n != null)
      if (n.getNodeName() != null)
        System.out.println(indent + n.getNodeName());
        traverse(indent + "  ", n.getFirstChild());
      if (n.getNodeValue() != null)
        System.out.println(indent + n.getNodeValue());
      traverse(indent, n.getNextSibling());
}Sample XSD:
<?xml version="1.0" encoding="ISO-8859-1"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
     <xsd:element name="item_list" type="ItemListType"/>
     <xsd:complexType name="ItemListType">
          <xsd:sequence>
               <xsd:element name="item_info" type="ItemInfoType" maxOccurs="unbounded"/>
          </xsd:sequence>
     </xsd:complexType>
     <xsd:complexType name="ItemInfoType">
          <xsd:sequence>
               <xsd:element name="name" type="xsd:string"/>
               <xsd:element name="price" type="xsd:double"/>
          </xsd:sequence>
     </xsd:complexType>
</xsd:schema>

Answer 1

Modified schema
<?xml version="1.0" encoding="ISO-8859-1"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:element name="item_list">     
<xsd:complexType>          
<xsd:sequence>               
<xsd:element ref="item_info" maxOccurs="unbounded"/>     
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="item_info">
     <xsd:complexType>          
<xsd:sequence>               
<xsd:element name="name" type="xsd:string"/>     
     <xsd:element name="price" type="xsd:double"/>     
     </xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>