trying to get nodeList through getting childnode value

Okay so I have this xml:

<employees>
   <employee>
     <name>John</name>
     <surname>Smith</surname>
   </employee>
  <employee>
     <name>Test</name>
     <surname>1</surname>
  </employee>
  <employee>
     <name>Cat</name>
     <surname>Dog</surname>
   </employee>
   <employee>
     <name>John</name>
     <surname>Bravo</surname>
   </employee>
</employees>

I am using Xpath to get the child node:

File f = new File("employees.xml");
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder =  builderFactory.newDocumentBuilder();
Document doc = builder.parse(f);
XPath xPath =  XPathFactory.newInstance().newXPath();

String val = "John";

String expression = "./employees[employee/name='"+ val +"']";
Node locatedNode = (Node) xPath.evaluate(expression, doc, XPathConstants.NODE);
Nodelist result = locatedNode.getParentNode().getChildNodes();

After that I use a for loop to loop through the nodelist to obtain surname of employees. In this case, I will get the two John's surname and add it to an array list

    List<Surname> sname = new ArrayList<Surname>;

for (int i = 0; i < result.getLength(); i++) {
    Node nNode = result.item(i);

     if (nNode.getNodeType() == Node.ELEMENT_NODE) {
         Element eElement = (Element) nNode; 
         String surname = eElement.getElementsByTagName("surname").item(0).getTextContent();
         sname.add(new Surname(surname));
     }
}

The problem is i kept on unable to get the Node, it kept throwing nullpointexception error. Is it that my expression is wrong or this line:

Nodelist result = locatedNode.getParentNode().getChildNodes();

is wrong?

What I wanted to get: Smith Bravo

Surnames of both John employee