Java: Most efficient method to iterate over all elements in a org.w3c.dom.Document?

Question

What is the most efficient way to iterate through all DOM elements in Java?

Something like this but for every single DOM elements on current org.w3c.dom.Docume

Answer 1

I also stumbled over this problem recently. Here is my solution. I wanted to avoid recursion, so I used a while loop.

Because of the adds and removes in arbitrary places on the list, I went with the LinkedList implementation.

/* traverses tree starting with given node */
  private static List traverse(Node n)
  {
    return traverse(Arrays.asList(n));
  }

  /* traverses tree starting with given nodes */
  private static List traverse(List nodes)
  {
    List open = new LinkedList(nodes);
    List visited = new LinkedList();

    ListIterator it = open.listIterator();
    while (it.hasNext() || it.hasPrevious())
    {
      Node unvisited;
      if (it.hasNext())
        unvisited = it.next();
      else
        unvisited = it.previous();

      it.remove();

      List children = getChildren(unvisited);
      for (Node child : children)
        it.add(child);

      visited.add(unvisited);
    }

    return visited;
  }

  private static List getChildren(Node n)
  {
    List children = asList(n.getChildNodes());
    Iterator it = children.iterator();
    while (it.hasNext())
      if (it.next().getNodeType() != Node.ELEMENT_NODE)
        it.remove();
    return children;
  }

  private static List asList(NodeList nodes)
  {
    List list = new ArrayList(nodes.getLength());
    for (int i = 0, l = nodes.getLength(); i < l; i++)
      list.add(nodes.item(i));
    return list;
  }