Hibernate: Self-mapping Parent/Child relationship using annotations

Yesterday I wrote about self mapping collections in Hibernate. I used XML mapping document to define the relationship. Today I would like to show how to achieve the same result using Java Annotations. So without further adu here is the java class:

@Entity
@Table(name = "CATALOGUE")
public class Catalogue implements Serializable {

    @Id
    @Column(name = "ID")
    private Integer id;

    @Column(name = "CONTENT", nullable = true)
    private String content;

    @ManyToOne
    @JoinColumn(name = "PARENT_ID")
    private Catalogue parent;

    @OneToMany(mappedBy = "parent")
    private Set<Catalogue> children = new HashSet<Catalogue>();

    public Catalogue() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Set<Catalogue> getChildren() {
        return children;
    }

    public void setChildren(Set<Catalogue> children) {
        this.children = children;
    }

    public void addChild(Catalogue child) {
        child.setParent(this);
        children.add(child);
    }

    public Catalogue getParent() {
        return parent;
    }

    public void setParent(Catalogue parent) {
        this.parent = parent;
    }
}