Use proxy objects, and implement your inheritance relationships there,
instead.
For example,
public class CarHomeProxy
{
private CarHome _carHome;
public Car findByPrimaryKey(CarPK carPK)
{
return _carHome.findByPrimaryKey( carPK );
}
}
public class SportsCarHomeProxy extends CarHomeProxy
{
private SportsCarHome _sportsCarHome;
public Car findByPrimaryKey(CarPK carPK)
{
// You might want to check here thet carPK is actually
// an instance of SportsCarPK before continuing...
return _sportsCarHome.findByPrimaryKey( (SportsCarPK)carPK );
}
}
...you get the idea. The SportsCarBean must extend CarBean, SportCarPK must
extend CarPK, and SportCar must extend Car. It's pretty convoluted, but this
approach is probably the best way to go about getting the sort inheritance
relationships you desire.
KurtC
-----Original Message-----
From: Tom Lepski [mailto:[EMAIL PROTECTED]]
Sent: Monday, August 07, 2000 5:11 PM
To: [EMAIL PROTECTED]
Subject: Re: A design question...
> >Consider that I have two classes Car and SportsCar where SportsCar
>extends
> >Car. Now, the system has objects of both classes. I want to model this
> >relationship in entity beans. How should I go about it? Can I have two
> >entity bean classes.. CarBean and SportsCarBean?
>You can use implementation inheritance to make SportsCarBean a subclass of
>CarBean. You can also use interface inheritance for the remote interface.
But, my SportsCar bean HAS to extend EntityBean. How can I have
implementation inheritance here?
>
>The problem is with the Home interface:
>
>public interface CarHome extends javax.ejb.EJBHome {
> Car findByPrimaryKey(CarKey key)
> }
> public interface SportsCarHome extends CarHome {
> SportsCar findByPrimaryKey(CarKey key);
> }
findByPrimaryKey() in SportsCar cannot return SprotsCar because then the
return types won't match.
Also, when I retrieve all the cars, I should also get SportsCars. I can't
call two findByXXX() methods (one for Car and one for SportsCar) to retrieve
all the cars.
Please help,
Tom.
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