An example of the use of @joincolumn in an Entity class to refer to itself.

Person.java

/**
 * A person.
 */
@Entity
@Table(name = "mm_usertable", catalog = "mmud", schema = "")
public class Person implements Serializable
{
    @Id
    @Basic(optional = false)
    @NotNull
    @Size(min = 3, max = 20)
    @Column(name = "name")
    @Pattern(regexp = NAME_REGEXP, message = "Invalid name")
    private String name;

    @ManyToMany(targetEntity = Person.class, fetch = FetchType.LAZY, cascade =
    {
        CascadeType.ALL
    })
    @JoinTable(name = "mm_ignore", joinColumns =
    {
        @JoinColumn(name = "fromperson", referencedColumnName = "name")
    }, inverseJoinColumns =
    {
        @JoinColumn(name = "toperson", referencedColumnName = "name")
    })
    private Set<Person> ignoringSet;
    @ManyToMany(mappedBy = "ignoringSet", targetEntity = Person.class, 
    fetch = FetchType.LAZY, cascade =
    {
        CascadeType.ALL
    })
    private Set<Person> ignoredSet;

    /**
     * Provides the set of persons that you are ignoring,
     */
    public Set<Person> getIgnoringSet()
    {
        return ignoringSet;
    }

    /**
     * Provides the set of persons that are ignoring you
     */
    public Set<Person> getIgnoredSet()
    {
        return ignoredSet;
    }

}