hibernate insert to a collection causes a delete then all the items in the collection to be inserted again

Question

I have a many to may relationship CohortGroup and Employee. Any time I insert an Employee into the CohortGroup hibernate deletes the group from the resolution table and ins

Answer 1

I have inserts acting the way I expect them to now. Thanks to Pascal and z5h, I have learned a lot. I believe I have the hashCode and equals implemented correctly. This never solved the problem for me though. Instead I have implemented an Intermediate Entity.

For what it is worth below are the mapping in my Employee, CohortGroup, and now CohortGroupMemeber classes.

Employee:

@OneToMany(mappedBy="member")
public List getMemberGroups(){
   return memberGroups;
}
public void setMemberGroups(List grps){
   memberGroups = grps;
}

CohortGroupMember

@ManyToOne
@JoinColumn(name="USERID")
public Employee getMember(){
    return emp;
}
public void setMember(Employee e){
    emp = e;
}
@ManyToOne
@JoinColumn(name="COHORT_GROUPID")
public CohortGroup getGroup(){
    return group;
}
public void setGroup(CohortGroup cg){
    group   = cg;
}

CohortGroup

@OneToMany(mappedBy="group")
public List getMembers(){
    return members;
}
public void setMembers(List emps){
    members = emps;
}

The book I followed for this is Java Persistence with Hibernate chapter 7.2.3