小编mh1*_*ack的帖子

早上好Stackoverflow,

我有问题,它给了我错误:

无法创建sessionFactory object.org.hibernate.AnnotationException:非法尝试将非集合映射为@OneToMany,@ ManyToMany或@CollectionOfElements:nl.scalda.pasimo.model.employeemanagement.EducationTeam.coachGroups

你知道为什么吗？

@OneToMany(cascade=CascadeType.ALL, targetEntity=CoachGroup.class)
@JoinColumn(name="id")
private TreeSet<CoachGroup> coachGroups = new TreeSet<>();
private SessionFactory factory;

private void initialiseFactory() {
    try {
        factory = new Configuration().configure().buildSessionFactory();
    } catch (Throwable ex) {
        System.err.println("Failed to create sessionFactory object." + ex);
        throw new ExceptionInInitializerError(ex);
    }
}