Traversing

Use

If you want to access an XML document directly, you can traverse the tree structure that represents the XML document.

The basic classes for traversing a document are:

org.w3c.dom.Node
org.w3c.dom.Element
org.w3c.dom.Text
org.w3c.dom.Comment
org.w3c.dom.Document
org.w3c.dom.NodeList
org.w3c.dom.NamedNodeMap

Example

The following examples clarify the process of traversing a tree structure:

Tip

public void traverse1(Node node) {
    do {
       System.out.println("Node: name=" + node.getNodeName() +
       ", value=" + node.getNodeValue() + ", type=" +
       node.getNodeType());
       if (node.getFirstChild() != null) {
        System.out.println("Processing children:");
        traverse1(node.getFirstChild());
      }
    }  while ((node = node.getNextSibling()) != null);
  }

Note

public void traverse2(Node node) {
    //Get the children of this Node
      NodeList children = node.getChildNodes();
   
      //go through all the children of the node
      for (int i=0; i<children.getLength(); i++) {
         //get the next child
         Node child = children.item(i);
         //get the type of the child
         short childType = child.getNodeType();
         if (childType == Node.ELEMENT_NODE) {
        //if the child is an Element then print the start and end
        //tags and recurse the content       
        String nodeName = child.getNodeName();
        System.out.print("<" + nodeName + ">");
        traverse2(child);
        System.out.print("</" + nodeName + ">");
      } else if (childType == Node.TEXT_NODE) {
        //if the child is a Text node just print the text content
        String data = child.getNodeValue();
        System.out.print(data);
    }
    }
  }

Note

public void traverse3(Node node, int indent) {
    for (int i = 0; i < indent; i++) {
      System.out.print("   ");
    }
    int type = node.getNodeType();
    switch (type) {
    case Node.ATTRIBUTE_NODE:
      System.out.println("ATTRIBUTE_NODE");
      break;
    case Node.CDATA_SECTION_NODE:
      System.out.println("CDATA_SECTION_NODE");
      break;
    case Node.COMMENT_NODE:
      System.out.println("COMMENT_NODE");
      break;
    case Node.DOCUMENT_FRAGMENT_NODE:
      System.out.println("DOCUMENT_FRAGMENT_NODE");
      break;
    case Node.DOCUMENT_NODE:
      System.out.println("DOCUMENT_NODE");
      break;
    case Node.DOCUMENT_TYPE_NODE:
      System.out.println("DOCUMENT_TYPE_NODE");
      break;
    case Node.ELEMENT_NODE:
      System.out.println("ELEMENT_NODE");
      NamedNodeMap atts = node.getAttributes();
      for (int i = 0; i < atts.getLength(); i++) {
        Node att = atts.item(i);
        traverse3(att, indent + 1);
      }
      break;
    case Node.ENTITY_NODE:
      System.out.println("ENTITY_NODE");
      break;
    case Node.ENTITY_REFERENCE_NODE:
      System.out.println("ENTITY_REFERENCE_NODE");
      break;
    case Node.NOTATION_NODE:
      System.out.println("NOTATION_NODE");
      break;
    case Node.PROCESSING_INSTRUCTION_NODE:
      System.out.println("PROCESSING_INSTRUCTION_NODE");
      break;
    case Node.TEXT_NODE:
      System.out.println("TEXT");
      break;
    default:
      System.out.println("???");
      break;
    }
    for (Node c = node.getFirstChild(); c != null; c =
    c.getNextSibling()) {
      traverse3(c, indent + 1);
    }
  }