java AnnotationException引用的属性不是（一个|多个）ToOne

Question

我试着建立一对一的关系。但我有一个错误：

AnnotationException Referenced property not a (One|Many)ToOne
on
com.student.information.service.Department.departmentId in mappedBy of com.student.information.service.DepartmentHead.department

这两个实体几乎完全相同。部门可以在没有部门负责人的情况下存在

部门。爪哇

@Entity
@Table(name="department", catalog="student")
public class Department {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer departmentId;

    @Column(name="dept_name")
    private String departmentName;

    @OneToMany(mappedBy="department",cascade = CascadeType.ALL)
    private List<Student> student; 

    @OneToOne(targetEntity=Department.class)
    private DepartmentHead departmenthead;
}       

系主任。爪哇

@Entity
@Table(name="departmenthead", catalog = "student")
public class DepartmentHead {

    //This is mapped with the department id

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    @Column(name="headname")
    private String headName;

    @OneToOne(mappedBy = "departmentId",fetch = FetchType.LAZY,cascade=CascadeType.ALL)
    @JoinColumn(name="dept_id")
    private Department department;  
}

原因：org。冬眠AnnotationException:引用的属性不是（一个|多个）ToOne：

有人能告诉我我犯了什么错误吗。在过去的两天里，我一直在苦苦挣扎，无法找到解决问题的方法。提前谢谢你的帮助