用xpath 读取xml 元素

public class ParseXml {
private static XPath xpath = null;
public static Document getDodument(String fileName) throws ParserConfigurationException, SAXException, IOException{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(fileName);
return document;
}
public static void main(String[] args) {
try {
Document document = getDodument("newfile.xml");
xpath = XPathFactory.newInstance().newXPath();
String name = xpath.evaluate("students/student[3]/name",document);
System.out.println(name);

}catch(Exception e){
e.printStackTrace();
}
}
}
======================newfile.xml=========================
<?xml version="1.0" encoding="UTF-8"?>
<students>
<student>
<name>jack1</name>
<age>26</age>
</student>
<student>
    <name>jack2</name>
<age>25</age>
</student>
<student>
    <name>jack3</name>
<age>23</age>
</student>
</students>