XML DOM & children nodes

[John Low]

i am parsing a simple xml document using dom and attempting to display the data in a JTree which will eliminate and group the node data together at the parent node level.
the basis for my code is from the java tutorial http://java.sun.com/xml/jaxp/dist/1.1/docs/tutorial/ with the following modifications to the AdapterNode toString() method:

    public String toString()
    {
      String s = "";
      String nodeName = domNode.getNodeName();
      if (!nodeName.startsWith("#"))
      {
        s += '[' + nodeName + "] ";
        if (nodeName.startsWith("group"))
        {
          for (int i=0; i<domNode.getChildNodes().getLength(); i++)
          {
            org.w3c.dom.Node node = domNode.getChildNodes().item(i);
            if (node.getNodeName().trim().equals("name"))
            {
              System.out.println("name node: " + node.getNodeValue());
              s += node.getNodeValue() + ", id: ";
            }
            if (node.getNodeName().trim().equals("id"))
            {
              System.out.println("id node: " + node.getNodeValue());
              s += node.getNodeValue();
            }
            // if there is an additional node, it represents subgroups
          }
        }
      }

my xml document has the following basic structure:

<specterGroups title="specterGroups">
    <group>
        <name>Group Name 1</name>
        <id>3</id>
        <groups>
            <group>
                <!-- the unique group id -->
                <name>Group Name 2</name>
                <id>1</id>
                <groups>
                    <group>
                        <name>Group Name 3</name>
                        <id>5</id>
                    </group>
                    <group>
                        <name>Group Name 4</name>
                        <id>6</id>
                    </group>
                </groups>
            </group>
            <group>
                <name>Group Name 5</name>
                <id>2</id>
            </group>
        </groups>
    </group>
    <group>
        <name>Group Name 6</name>
        <id>4</id>
    </group>
</specterGroups>

the JTree looks like this:

-[specterGroups]
  - [group] null, id: null
    - [name] Group Name 1
    - [id] 3
    - [groups]
      -[group] null, id: null
       - [name] Group Name 2
       - [id] 1
       - [groups]
         - etc...
  - [group] null, id: null
    - [name] Group Name 6
    - [id] 4

so, given a [group] node which must have [name] and [id] children and optionally a [groups] node for further nesting. however, since the level of detail shown in the JTree is unnecessary for me (all i want is the [group] entry with the nodeValues of it's children who are not a node of name [groups]). so ideally, my JTree should look like:

- [specterGroups]
  - [group] Group Name 1, id: 3
  - [groups]
    - [group] Group Name 2, id: 1
    - [groups]
      - [group] Group Name 3, id: 5
      - [group] Group Name 4, id: 6

etc...
the problem is that when i take the parent node ([group]) and getChildNodes(), i can invoke on a node of that list, node.getNodeName() and it will return the proper name of the node. however, if i invoke node.getNodeValue() on the same parent, it returns a null value, despite the fact that when you expand the JTree, the specified nodes and values are present.
sorry for the long message. any ideas anyone?

[Jeanne Boyarsky]

Elements return null for nodeValue(). For that matter, so does everything except attributes, CDATA, comments, processing instructions and text.
You have to get the attributes for the parent node or loop through its children to get any useful info.

[Cindy Glass]

Moving to the XML forum.

[William Brogden]

There is a VERY handy table in the org.w3c.dom.Node JavaDocs that shows what is returned for nodeName and nodeValue for all types of nodes. That null return trips up a lot of people.
Bill