Xpath expression evaluates to an empty nodelist

Question

I am having trouble parsing an xml file and retrieve data from it. Below is the xml and code snippet. -----XML (test.xml)-----

<?xml version="1.0" encoding="utf-8"?>
<root>
<Server>
<IPAddress>xxx.xxx.xxx.xxx</IPAddress>
<UserName>admin</UserName>
<Password>admin</Password>
</Server>

-----Code Snippet: -----

public static String getInput(String element)
{
    String value = "";
    try {

        File inputFile = new File("test.xml");
        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = dbFactory.newDocumentBuilder();
        Document inputData = builder.parse(inputFile);
        inputData.getDocumentElement().normalize();
        String[] elementArray = element.split("/");

        XPath xPath =  XPathFactory.newInstance().newXPath();
        String xpathExpression = element;

        System.out.println("Xpath Expression:" + xpathExpression);
                NodeList node = (NodeList) xPath.compile(xpathExpression).evaluate(inputData, XPathConstants.NODESET);
        System.out.println(node.getLength());

        if (null != node){
                System.out.println(node.getLength());
                for (int i=0; i<node.getLength(); i++){
                    System.out.println(i);
                    System.out.println("Node count =" + node.getLength() + ";" + 
                        "Node Name =" + node.item(i).getNodeName()); 

                if (node.item(i).getNodeName() == elementArray[1]){
                    System.out.println(node.item(i).getNodeName()+ "=" + node.item(i).getNodeValue());
                    value = node.item(i).getNodeValue();
                }

            }   
        }           

    }   catch (Exception e) {
        e.printStackTrace();
    }

    return value;
}

The code compiles OK. While running, it just doesn't seem to find the nodes "Server" and it's child "IPAddress". The call to getInput() above would come from main in the format below:

getInput("Server/IPAddress");

Not sure where it's going wrong and I am really new to Xpath. I was wondering if someone can help.

Thanks!

Answer 1

The outermost element is <root/> , not <server/> . Your query needs to be

getInput("root/Server/IPAddress")

if you want to use the full path, or even

getInput("/root/Server/IPAddress")

to indicate you're starting at the root element. Alternatively, you could have XPath to search for all server elements all over the document:

getInput("//Server/IPAddress")

---

All of those will output

Xpath Expression:root/Server/IPAddress
1
1
0
Node count =1;Node Name =IPAddress

instead of

Xpath Expression:Server/IPAddress
0
0

---

You could somehow prepend one of the prefixes of your choice in the getInput() function, of course.