XML Tree Parsing problems

Question

I am trying to make a program that will read the tree of an xml file and later store the data in a different format...
At the moment it reads part of the tree. but then a null pointer exception occurs on the line marked (***) in the .java file attached.
It starts at the base element ('servers' in this case) then finds if it has child nodes, if so it stores them, again and again untill it finds text, it will then print the text to screen, and remove the child from the previous node. If a node no longer has any children it is removed from the list and then the next node is found...
The problem being is that is isnt correctly working, as some of the nodes in the pastNodes arraylist are being replaced by one of their child nodes....so when it comes to the point where the list gets shorter and the next node needs to be found it has an incorrect tree list in pastNodes and dies on me.
The reason for doing it like this is so that i can list the values in a tree like format in an array (eventually) such as 'servers.server.ComputerName' has value 'Bobs_PC' etc. as the program that wrote this leaves multiple smae named variables with different types of value...e.g. like 100 'Name' tags but some refer to a drive name and others to services names.
Any ideas?
Cheers for any help.
Here is my code...sorry that its so long :(
public void read(String xmlToRead){
          System.out.print("\n* Reading '"+xmlToRead+"'...");
          try {
     DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
     DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
     Document doc = docBuilder.parse(new File(xmlToRead));
     // normalize text representation
     doc.getDocumentElement ().normalize ();
     NodeList listOfNodes = doc.getElementsByTagName("servers");
     ArrayList pastNodes= new ArrayList();
     pastNodes.add(listOfNodes.item(0));
     while(((Node) pastNodes.get(pastNodes.size()-1)).hasChildNodes()){
          System.out.println("\n------");
          //stores all new nodes with children
          if(((Node) pastNodes.get(pastNodes.size()-1)).getFirstChild().getNodeName() != "#text"){
               pastNodes.add(((Node) pastNodes.get(pastNodes.size()-1)).getFirstChild());
               System.out.println("NODE ADDED");
          System.out.println("pastNodes Path:");
          int x=0;
          while(x<pastNodes.size()){
               System.out.println(x+": "+((Node) pastNodes.get(x)).getNodeName());
               x++;
               //print the text value
          Node child = ((Node) pastNodes.get(pastNodes.size()-1)).getFirstChild();
          //*** NULL POINTER HERE
          //System.out.println(child.getNodeName()+" / "+child.getNodeType());
          if(child != null && child.getNodeName()=="#text"){System.out.println("Value: "+child.getNodeValue());}
          //remove child node from parent once read
          if(((Node) pastNodes.get(pastNodes.size()-1)).hasChildNodes()){
               Node newNode = ((Node) pastNodes.get(pastNodes.size()-1)).removeChild(child);
               pastNodes.remove(pastNodes.size()-1);
               System.out.println("Child Removed: "+child.getNodeName());
               pastNodes.add(newNode);
               //deletes a node from list if it does not have any more children.
               if(!((Node) pastNodes.get(pastNodes.size()-1)).hasChildNodes()){
                    System.out.println("Removed Past Node : "+(pastNodes.size()-1)+"/"+((Node) pastNodes.get(pastNodes.size()-1)).getNodeName());
                    pastNodes.remove(pastNodes.size()-1);
     System.out.println(((Node) pastNodes.get(pastNodes.size()-1)).hasChildNodes());
     }catch (SAXParseException err) {
     System.out.println ("** Parsing error" + ", line " + err.getLineNumber () + ", uri " + err.getSystemId ());
     System.out.println(" " + err.getMessage ());
     }catch (SAXException e) {
     Exception x = e.getException ();
     ((x == null) ? e : x).printStackTrace ();
     }catch (Throwable t) {
     t.printStackTrace ();
          System.out.print("Done\n");
** And a snippet of the output at the console

Answer 1

Here is my code...sorry that its so long :(There is no problem if the code is long. But atleast it should be formatted to help us read it.
Node child = ((Node) pastNodes.get(pastNodes.size()-
1)).getFirstChild();
          //*** NULL POINTER HERE
//System.out.println(child.getNodeName()+"
deName()+" / "+child.getNodeType());I think you get the NullPointerException when you call a method on the child node. The getFirstChild() method could return null if there is no child node. It is always good to check for nulls.