求救 cannot find symbol

Student 类：
package com.nj180.hibernate.day01;public class Student {
private int id;
private String name;
private String phone;
private String birthday;

public Student(){
this.id = 123456;
this.name = "无名氏";
this.phone = "12345678901";
this.birthday = "19990101";
}

public int getId(){
return this.id;
}
}
StudentService 类：
package com.nj180.hibernate.day01;
import java.io.*;
import java.util.Collection;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import com.nj180.hibernate.day01.Student;
import org.hibernate.cfg.Configuration;
public class StudentService {
private static SessionFactory factory = null;
static{
try{
Configuration config = new Configuration();
factory = config.buildSessionFactory();
}catch(Throwable e){
System.err.println("Initial SessionFactory err!");
throw new ExceptionInInitializerError(e);
}
}
public void save(Student student){
//声明会话和事务
Session session=null;
Transaction trans=null;
try{
//建立会话
session = factory.openSession();
//开始事务
trans = session.beginTransaction();
session.save(student);
trans.commit();
//捕获异常
}catch(RuntimeException e){
//异常存在则事务回滚，打印异常堆栈
trans.rollback();
e.printStackTrace();
throw e;
}finally{
//无论情况如何关闭会话
session.close();
}
}
//查询所有记录
@SuppressWarnings("finally")
public Student findById(int id){
Student student = null;
Session session = null;
Transaction trans = null;
try{
session = factory.openSession();
trans = session.beginTransaction();
student = (Student) session.get(Student.class, id);
trans.commit();
}catch(RuntimeException e){
trans.rollback();
e.printStackTrace();
}finally{
session.close();
return student;
}
}
@SuppressWarnings("finally")
public Collection find(){
Collection student = null;
Session session = null;
Transaction trans = null;
try{
session = factory.openSession();
trans = session.beginTransaction();
Query  query = session.createQuery("select student from Student student");
//query最后以list形式返回数据，list是Collection集合下的一种实现方法，
//所以定义student为Collection比较合适
student = query.list();
trans.commit();
}catch(RuntimeException e){
trans.rollback();
e.printStackTrace();
}finally{
session.close();
return student;
}
}
}
编译StudentService时报错：
com/nj180/hibernate/day01/StudentService.java:8: cannot find symbol
symbol  : class Student
location: package com.nj180.hibernate.day01
import com.nj180.hibernate.day01.Student;
                                 ^
com/nj180/hibernate/day01/StudentService.java:21: cannot find symbol
symbol  : class Student
location: class com.nj180.hibernate.day01.StudentService
        public void save(Student student){
                         ^
com/nj180/hibernate/day01/StudentService.java:46: cannot find symbol
symbol  : class Student
location: class com.nj180.hibernate.day01.StudentService
        public Student findById(int id){
               ^
com/nj180/hibernate/day01/StudentService.java:47: cannot find symbol
symbol  : class Student
location: class com.nj180.hibernate.day01.StudentService
                Student student = null;
                ^
com/nj180/hibernate/day01/StudentService.java:54: cannot find symbol
symbol  : class Student
location: class com.nj180.hibernate.day01.StudentService
                        student = (Student) session.get(Student.class, id);
                                   ^
com/nj180/hibernate/day01/StudentService.java:54: cannot find symbol
symbol  : class Student
location: class com.nj180.hibernate.day01.StudentService
                        student = (Student) session.get(Student.class, id);
                                                        ^
6 errors
请求高手帮我解决一下，我写了另一个简单的测试类 声明一个Student类也不行!我感觉是Student类有问题，但我就是看不出来！