What is the shortest way to pretty print a org.w3c.dom.Document to stdout?

private void printNode(Node rootNode, String spacer) {
    System.out.println(spacer + rootNode.getNodeName() + " -> " + rootNode.getNodeValue());
    NodeList nl = rootNode.getChildNodes();
    for (int i = 0; i < nl.getLength(); i++)
        printNode(nl.item(i), spacer + "   ");
}

Try jcabi-xml with one liner:

String xml = new XMLDocument(document).toString();

This is the dependency you need:

<dependency>
  <groupId>com.jcabi</groupId>
  <artifactId>jcabi-xml</artifactId>
  <version>0.14</version>
</dependency>

Call printDocument(doc, System.out), where that method looks like this:

public static void printDocument(Document doc, OutputStream out) throws IOException, TransformerException {
    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer transformer = tf.newTransformer();
    transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
    transformer.setOutputProperty(OutputKeys.METHOD, "xml");
    transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
    transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");

    transformer.transform(new DOMSource(doc), 
         new StreamResult(new OutputStreamWriter(out, "UTF-8")));
}

(The indent-amount is optional, and might not work with your particular configuration)

How about:

OutputFormat format = new OutputFormat(doc);
format.setIndenting(true);
XMLSerializer serializer = new XMLSerializer(System.out, format);
serializer.serialize(doc);