请教关于toString的问题，打印对象为什么不调用我重写的toString方法？

Question

今天在学MyBatis的时候需要打印student对象，如下

public class Test {
    public static void main(String[] args) throws IOException{
        Reader reader = Resources.getResourceAsReader("conf.xml");
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession session = sessionFactory.openSession();
        String statement = "entity.studentMapper.queryStudentByStuno";
        Student student = session.selectOne(statement,1);
        System.out.println(student);        
        session.close();    }
}

重写的toString方法为

public String toString() {
        return this.stuNo +","+this.stuName +","+this.stuAge+","+this.graName;
    }

输出结果为
entity.Student@35aea049
这应该是未重写的toString放法吧，可是我已经重写了toString而且显示了overrides，为什么不调用我重写的toString呢？

Answer 1

Student类加上实现Serializable序列化接口，参考如下

public class  Student   implements Serializable     {
//serialVersionUID可以用ide自动生成
private static final long serialVersionUID = -983676524367844782L;
…
}