<List> <User userId="1"/> </List>
NodeList list = XPathAPI.selectNodeList( doc, "/List/User" ); Node userId = XPathAPI.selectSingleNode(user, "./User/@userId");
Wrong, you're already on the User element. Try this
NodeList list = XPathAPI.selectNodeList( doc, "/List/User" ); Node userId = XPathAPI.selectSingleNode(user, "./@userId");
Or this
NodeList list = XPathAPI.selectNodeList( doc, "/List/User/@userId" );
