没有定义类Namecomparator 如何在TestStudent类中定义comparator接口

import java.util.Comparator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

   
  public class NameComparator implements Comparator<Student> {
 
 @Override
 public int compare(Student arg0, Student arg1) {

  String Name01=arg0.getName();
  String Name02=arg1.getName();
  int n=Name01.compareTo(Name02);
  return n;
 } 
 }

    public class StudentTest {   
    public static void main(String[] args){
      Student stu1=new Student(40,20,"peter");
     Student stu2=new Student(28,5,"angle");
     Student stu3=new Student(35,18,"tom");
     List<Student>list=new ArrayList<Student>();
     list.add(stu1);
     list.add(stu2);
     list.add(stu3);
     System.out.println("排序前：");
     for(Student n:list) {
      System.out.println(n);
     }
     Collections.sort(list, new Comparator());
 System.out.println("升序后：");
 for(Student n:list) {
  System.out.println(n);
 }
 }  
    }