我需要帮助，我得到了前面提到的异常。我哪里出错了？在从类到表的Map中，我使用了以下代码：

private String userId;
private String password;

下面是我编写查询的类。

public class LoginManager extends HibernateUtil {
    private String loginId;

    public String checkCredentials(String userId, String password) {

        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        try {
          loginId = (String) session.createQuery("select user_id from com.project.model.Login where user_id=:userId and password=:password") 
                                   .setParameter("userId",userId)
                                   .setParameter("password", password)
                                   .list().toString();
        } catch (HibernateException e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        }
        session.getTransaction().commit();
        return loginId;
    }
}

实体

@Entity
@Table(name = "Login")
public class Login implements Serializable {
    private static final long serialVersionUID = 2L;
    private String userId;
    private String password;

    @Id
    @Column(name = "user_id")
    public String getUserId() {
        return userId;
    }

    public void setUser_id(String userId) {
        this.userId = userId;
    }

    @Column(name = "password")
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}