ManyToMany with interfaces

[amitkhanna]

Hi

I have an application in which I have 4 entities User, Group, Message and Ticket each entity has an id that is being generated by their corresponding sequences. I'm using JPA with Hibernate.

@Entity
class User extends SomeClassA{
     @Id
     @GeneratedValue(generator="seqUser")
     int userId;
     ... other fields, getter and setters ....
}

@Entity
class Group extends SomeClassB{
     @Id
     @GeneratedValue(generator="seqGrp")
     int groupId;
     ... other fields, getter and setters ....
}
@Entity
class Message extends SomeClassC{
     @Id
     @GeneratedValue(generator="seqMsg")
     int msgId;
     ... other fields, getter and setters ....
}
@Entity
class Ticket extends SomeClassD{
     @Id
     @GeneratedValue(generator="seqTic")
     int ticId;
     ... other fields, getter and setters ....
}

The application is working fine. Now I need to make few changes in this application:
1. Each Message and Ticket needs to be approved.
2. There can be multiple approvers for each Message/Ticket.
3. Each User/Group will have an approval queue.

I've thought of implementing the changes as follows:
1. User and Group will implement interface 'Approver'.
2. Message and Ticket will implement interface 'Approvable'.
3. User and Group will have a List<Approvable> approvalQueue;
4. Message and Ticket will have a List<Approver> approvers;

Can anyone help me understand how this can be done?

Thanks
Amit Khanna

[dr_pompeii]

Hello

A POJO/Entity class should represent only a noun without an action or verb, therefore is not wise, and I never have seen a POJO/Entity implementing some interface, you are mixing concers

such logic must be located in some Service/BO class

[amitkhanna]

Thanks for your reply. I understand that what i'm trying is wrong. Can you suggest a better way of implementing the three changes I mentioned:

1. Each Message and Ticket needs to be approved.
2. There can be multiple approvers for each Message/Ticket.
3. Each User/Group will have an approval queue.