Duvidas com o JDOM

Assuntos Gerais Agile
#1

Galera do Portal,

Estou tentando usar o JDOM para mudar os dados do meu XML. So que esta dando java.lang.ClassCastException.

Segue o meu XML e o codigo que estou rodando.

Primeiro Codigo XML

<?xml version="1.0" encoding="UTF-8"?> 
<catalog xmlns:journal="http://www.w3.org/2001/XMLSchema-Instance" > 
  <journal:journal title="XML"  publisher="IBM developerWorks"> 
      <article journal:level="Intermediate"              
            date="February-2003">   
         <title>Design XML Schemas Using UML</title> 
         <author>Ayesha Malik</author>  
      </article>
  </journal:journal> 
  <journal title="Java Technology"  publisher="IBM       
        developerWorks"> 
      <article level="Advanced" date="January-2004">   
          <title>Design service-oriented architecture    
                 frameworks with J2EE technology</title> 
          <author>Naveen Balani</author>  
      </article>
      <article level="Advanced" date="October-2003">   
          <title>Advance DAO Programming</title> 
          <author>Sean Sullivan </author>  
      </article>
  </journal> 
  <vcs teste="vcs">
      vcs
  </vcs>
</catalog>

Agora segue o meu codigo java

import java.io.File;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;

public void lerXml(){
        try {
            Object o = null;
           File xmlDocument = new File("D:\\temp\\TesteLog4J\\src\\teste.xml");
           SAXBuilder saxBuilder = new SAXBuilder("org.apache.xerces.parsers.SAXParser");
           org.jdom.Document jdomDocument = saxBuilder.build(xmlDocument);
           org.jdom.Attribute levelNode = (org.jdom.Attribute)(XPath.selectSingleNode(jdomDocument,"/catalog//vcs[@teste='vcs']"));
           levelNode.setValue("Intermediate");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

Agora quando eu uso essa linha

org.jdom.Attribute levelNode = (org.jdom.Attribute)(XPath.selectSingleNode(jdomDocument,"/catalog//journal[@title='JavaTechnology']" + "//article[@date='January-2004']/@level"));

O erro que da é java.lang.NullPointerException

Valeu mais uma vez galera!!!

#2