Question

I am trying to build server that sends a xml file to client. I am getting info from db and wants to build from that xml file.

But I have a problem with:

DocumentBuilder documentBuilder = null;
Document doc =documentBuilder.newDocument();

I am getting NullPointerException. Here is me full code:

public void createXmlTree() throws Exception {
  //This method creates an element node
  DocumentBuilder documentBuilder = null;
  Document doc =documentBuilder.newDocument();

  Element root = doc.createElement("items");
  //adding a node after the last child node of the specified node.

  doc.appendChild(root);
  for(int i=0;i<db.stories.size();i++){
    Element child = doc.createElement("item");
    root.appendChild(child);

    Element child1 = doc.createElement("title");
    child.appendChild(child1);

    Text text = doc.createTextNode(db.stories.get(i).title);
    child1.appendChild(text);

    //Comment comment = doc.createComment("Employee in roseindia");
    //child.appendChild(comment);

    Element child2 = doc.createElement("date");
    child.appendChild(child2);

    Text text2 = doc.createTextNode(db.stories.get(i).date);
    child2.appendChild(text2);

    Element child3 = doc.createElement("text");
    child.appendChild(child3);

    Text text3 = doc.createTextNode(db.stories.get(i).text);
    child3.appendChild(text3);

    root.appendChild(child3);

Answer 1

Well yes, you would get a NullPointerException. You’re calling a method on a null reference – very clearly, given that you’ve assigned the documentBuilder a null value on the line before. You need to get an instance of DocumentBuilder to start with. For example:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = factory.newDocumentBuilder();