XPath Query Not Returning any Results in Java

Mon, 25 Mar 2013 07:25:27 +0000

In looking over documentation on XPath queries it seemed easy enough to be able to pull out values from XML, but try as I might I kept getting no results back. Even searching on the root element “/elementName” didn’t return any results. Of course, as with all things Java there’s a trick and that trick is to call setNamespaceAware(). Here’s a quick and dirty example…

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(false); // NEVER FORGET THIS
DocumentBuilder builder = domFactory.newDocumentBuilder();
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr = xpath.compile("/items/item[@id='2']");
return (NodeList)expr.evaluate(domDocument, XPathConstants.NODESET);

Output a DOM Document as XML using Java

Sat, 23 Mar 2013 02:23:28 +0000

Ok, here’s another nerdy post for all the java developers out there. Hopefully it saves you some time.

Let’s say you have a XML DOM Document that you’ve been modifying in your code, and now want to write it back out as XML. One would think there would be a nice toXml() method or something on the Document, but there isn’t. Instead, make sure you have the xalan.jar file on your class path and use this function…

public static String getDomDocumentAsXml(org.w3c.dom.Document domDocument)
{
	try
	{
		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer transformer = tf.newTransformer();
		transformer.setOutputProperty(OutputKeys.INDENT, "yes");
		StreamResult xmlOutput = new StreamResult(new StringWriter());
		transformer.transform(new DOMSource(domDocument), xmlOutput);
		return xmlOutput.getWriter().toString();
	}
	catch (Exception e) { e.printStackTrace(); return null; }
}

Xml on MarkJacobsen.net

XPath Query Not Returning any Results in Java

Output a DOM Document as XML using Java