Java Alternative to C#'s WriteAttributeString()

Question

In C#, there's a method to write attributes to an XML element:

public void WriteAttributeString(string? prefix, string localName, string? ns, string? value);

What I have found in Java is:

Attr createAttributeNS(String namespaceURI, String qualifiedName)

But it seems lacking two parameters. As far as I understand, ns == namespaceURI, and localName == qualifiedName.

Is there a similar method to achieve the same thing in Java? Or do I have to implement my own version (consequently, extending Document)?

Answer 1

You could call setAttributeNS on org.w3c.dom.Element.

Suppose you want to generate an output like the following:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<root>
    <child xmlns:pfx="http://www.example.com" answer="42"/>
</root>

You could use something similar to the following code:

childElement.setAttributeNS("http://www.w3.org/2000/xmlns/","xmlns:pfx","http://www.example.com");
childElement.setAttribute("answer", "42");

A complete, self-contained example might look like this:

package com.software7.test;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;

public class Main {

    public static void main(String[] args) throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware(true);
        DocumentBuilder docBuilder = dbf.newDocumentBuilder();
        Document document = docBuilder.newDocument();
        Element rootElement = document.createElement("root");
        document.appendChild(rootElement);

        Element childElement = document.createElement("child");
        rootElement.appendChild(childElement);
        childElement.setAttributeNS("http://www.w3.org/2000/xmlns/","xmlns:pfx","http://www.example.com");
        childElement.setAttribute("answer", "42");

        Transformer transformer = TransformerFactory.newInstance().newTransformer();
        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.transform(new DOMSource(document), new StreamResult(System.out));
    }

}