Creating a custom XPath function to modify a node-set in Java

Question

I am creating a custom XPath function in Java that modifies the text-nodes in a node-set. I need to pass in a node-set, have the code loop through every node and return a node-set. I have seen many examples of custom XPath functions that modify strings, but none that take in a node set and return a node set successfully. I also don't know how to map the returning node-set.

Take this source XML for example.

<Library>
    <Bookshelf>
        <Book>alice in wonderland</Book>
        <Book>the giving tree</Book>
            <Author>shel silverstein</Author>
    </Bookshelf>
</Library>

Then I want this to be my target XML. I chose to capitalize the first letter of each word, but this is just an example. Don't worry about the text modification part, I got that.

<Library>
    <Bookshelf>
        <Book>Alice In Wonderland</Book>
        <Book>The Giving Tree</Book>
            <Author>Shel Silverstein</Author>
    </Bookshelf>
</Library>

The biggest thing here is that I want to implement this as a custom XPath function using Java so that it can be drag-and-dropped in Designer mode. And I am using a File Adapter on each side of this transformation, so the structure of all the nodes is already given and I have to make my results fit in.

Answer 1

You need to create your own implementation of NodeList. Something like what I use:

package org.gramar.model;

import java.util.List;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class NodeArray implements NodeList {

    private Node nodes[];

    public NodeArray(Node[] nodes) {
        this.nodes = nodes;
    }

    public NodeArray(List<Node> nodes) {
        this.nodes = new Node[nodes.size()];
        nodes.toArray(this.nodes);
    }

    @Override
    public Node item(int index) {
        return nodes[index];
    }

    @Override
    public int getLength() {
        return nodes.length;
    }

}

Your XPathFunction code would have something like this:

ArrayList<Node> nodes = ... logic to gather the nodes you want to return
return new NodeArray(nodes);