JAVA element.getElementsByTagName Restrict to Top Level

Question

I have an XML file as follows:

<rootNode>
    <link>http://rootlink/</link>
    <image>
        <link>http://imagelink/</link>
        <title>This is the title</title>
    </image>
</rootNode>

The XML Java code using DOM is as follows:

NodeList rootNodeList = element.getElementsByTagName("link");

This will give me all of the "link" elements including the top level and the one inside the "image" node.

Is there a way to just get the "link" tags for rootNode within one level and not two such as is the case for the image link? That is, I just want the http://rootlink/ "link".

Answer 1

You could use XPath:

XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
NodeList links = (NodeList) xpath.evaluate("rootNode/link", element,
    XPathConstants.NODESET);

Answer 2

I couldn't find any methods to do that either so I wrote this helper function,

 public static List<Element> getChildrenByTagName(Element parent, String name) {
    List<Element> nodeList = new ArrayList<Element>();
    for (Node child = parent.getFirstChild(); child != null; child = child.getNextSibling()) {
      if (child.getNodeType() == Node.ELEMENT_NODE && 
          name.equals(child.getNodeName())) {
        nodeList.add((Element) child);
      }
    }

    return nodeList;
  }

Answer 3

If you can use JDOM instead, you can do this:

element.getChildren("link");

With standard Dom the closest you can get is to iterate the child nodes list (by calling getChildNodes() and checking each item(i) of the NodeList, picking out the nodes with the matching name.

Answer 4

I know this is an old question, but nonetheless I have an alternative solution to add.

It's not the most efficient, but works:

Get all the children using getElementsByTagName, then just check each one has the same parent to the one you started with.

I use this because I have a set of results, each result can have results nested inside it. When I call my Result constructor I need to add any nested results, but as they themselves will look for their own children I don't want to add children to the current level (their parent will add them).

Example:

NodeList children = resultNode.getElementsByTagName("result");
for(int i = 0; i<children.getLength(); i++){
   // make sure not to pick up grandchildren.
   if(children.item(i).getParentNode().isSameNode(resultNode)){
        addChildResult(new Result((Element)children.item(i)));
    }
}

Hope this helps.