Question

I have the following:

public static void main(String args[]) {

     // upload config' data for program - param' are path and Xml's Root node/ where to get data from
     confLoader conf = new confLoader("conf.xml", "config"); 

     System.out.println(conf.getDbElement("dataSource") );
     System.out.println(conf.getDbElement("dataSource") );
     System.out.println(conf.getDbElement("dataSource") );  // Fails 
...

---

The code that’s responsible to build the DOM and parse from (‘getDbElement()’):

public class confLoader{

 DocumentBuilderFactory docBuilderFactory;
 DocumentBuilder docBuilder;
 Document doc;
 NodeList nList;

 public confLoader(String path, String XmlRoot){

    try {
            docBuilderFactory = DocumentBuilderFactory.newInstance();
            docBuilder = docBuilderFactory.newDocumentBuilder();
            doc = docBuilder.parse(new File(path));
            // normalize text representation
            doc.getDocumentElement().normalize();                
    nList = doc.getElementsByTagName(XmlRoot);

  } catch (Exception e) {
    e.printStackTrace();
  } 
}

public String getDbElement(String element) {

    Node nNode = nList.item(0); //  1st item/node - sql
    try {
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {     /////  Line 36 - Problematic

            Element eElement = (Element) nNode;
            return (((Node) eElement.getElementsByTagName(element).item(0).getChildNodes().item(0)).getNodeValue());
        }
    } catch (Exception ex) {
        System.out.println("Error retrieving " + element + " :" + ex.getMessage());//Thread.dumpStack();
         ex.printStackTrace();
      }
    return "not available";
 }

}

---

stacktrace for given code:

  jdbc:mysql://localhost:...
  java.lang.NullPointerException
  jdbc:mysql://localhost:...
  Error retrieving dataSource :null
  not available
  at exercise.confLoader.getDbElement(confLoader.java:36)
  at exercise.Exercise.main(Exercise.java:22)

      Line 36 : if (nNode.getNodeType() == Node.ELEMENT_NODE)

The xml parsing is done twice, and for the 3rd time I try to parse from Xml, I get the NullPointerException.

Answer 1

Problem solved by removing gnujaxp.jar from the build path.