[求助]DOM访问xml出了点问题!请那位大哥帮忙解决一下

package org.myxml.test;

import java.io.File;
import java.io.IOException;
import org.w3c.dom.*;
import javax.xml.parsers.*;
import org.xml.sax.SAXException;
public class Test {
    public static void main(String[] args) {
        
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder db = dbf.newDocumentBuilder();
            System.out.println(dbf);
//这儿输出:com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl@be2358
            System.out.println(db);
/这儿则输出:com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl@1027b4d
            File file = new File("student.xml");
            Document doc = db.parse(file);
            System.out.println(doc);
//这儿则输出:[#document: null]

            NodeList nl = doc.getElementsByTagName("sutdent");

            int len = nl.getLength();

            for(int i=0; i < len; i++){
                Element eltStu = (Element)nl.item(i);
                Node eltName = eltStu.getElementsByTagName("name").item(0);
                Node eltSex = eltStu.getElementsByTagName("Sex").item(0);

                String name = eltName.getFirstChild().getNodeValue();
                String sex = eltSex.getFirstChild().getNodeValue();

                System.out.print("姓名:");
                System.out.println(name);
                System.out.print("性别:");
                System.out.println(sex);
            }
        }
        catch(ParserConfigurationException e) {
            e.printStackTrace();
        }
        catch(SAXException e){
            e.printStackTrace();
        }
        catch(IOException e){
            e.printStackTrace();
        }
            
    }
}
麻烦那位大侠帮忙解决一下啊`` 运行没有结果!!

没有人吗`?
为什么Document doc = db.parse(file);这儿解析为XML时``反回是的空啊`

查了很我资料啊`` 都是这样的` 不明白啊```