求帮助，编译时不报错。运行时报错。

Question

package n;

public interface Comparable<Student> {
   public int compareTo(Student s);
}

package n;

import java.util.Set;
import java.util.TreeSet;

public class Student implements Comparable<Student> {
       int id;
       String name;
       public Student(int id, String name){
           this.id = id;
           this.name = name;
       }
       public int compareTo(Student s){
           if(this.id < s.id) return -1;
           else if(this.id > s.id) return 1;
           else return 0;
       }
       public String toString(){
           return "<" + this.id + "." + this.name + ">";
       }
    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        Student[] stud = new Student[]{
                new Student(1002, "张三"),
                new Student(1003, "李四"),
                new Student(1001, "王五")
        };
        Set<Student> ts = new TreeSet<Student>();
        for(int i = 0; i < stud.length; i ++)
            ts.add(stud[i]);
            System.out.println(ts);
    }

  
}

Answer 1

报什么错？