How to get all element names with JDOM 2 via XPath in Java 7? - xpath-2.0

Question

I have a XML file like the following.
<?xml version="1.0" encoding="UTF-8"?>
<Site>
<Name>MySite</Name>
<Groups>
<Default></Default>
<GroupA></GroupA>
</Groups>
</Site>
I want to get all names of Groups' children elements (in this example 'Default' and 'GroupA') as a list of strings. I was trying the following.
public List<String> getGroupNames() {
List<String> names = new ArrayList<String>();
XPathExpression<Text> xpath = XPathFactory.instance().compile(
"/Site/Groups/*/name()", Filters.text());
List<Text> elements = xpath.evaluate(document);
if (elements.size() > 0) {
for (Text text : elements) {
names.add(text.getText());
}
return names;
}
return null;
}
This fails hard with the following exception.
class org.jaxen.saxpath.XPathSyntaxException: /Site/Groups/*/name(): 20: Expected node-type
What is the proper syntax for that? I do not understand the exception.

Answer 1

It seems the XPathFactory instance you use only supports XPath 1.
You need to load a library supporting XPath 2, before being able using xpath 2. E.g: with SAXON:
import net.sf.saxon.om.NamespaceConstant;
String objectModel = NamespaceConstant.OBJECT_MODEL_SAXON;
System.setProperty("javax.xml.xpath.XPathFactory:"+objectModel, "net.sf.saxon.xpath.XPathFactoryImpl");