You need to implement equals() in your Pharmacy implementation class.
What's happening is that either the object in the collection or the object
that you're passing to remove() is a Proxy. The default implementation of
equals() (which is used by remove()) just uses ==. Since the objects are
not the same object, remove() doesn't find the one you're trying to get
rid of.
Here's a sample implementation (for a PharmacyImpl class implementing a
Pharmacy interface - adjust names as necessary):
public boolean equals(Object o) {
if (o == null) return false;
if (o == this) return true;
// Double-dispatch to remove any Proxy from the picture
if (java.lang.reflect.Proxy.isProxyClass(o.getClass())) {
return o.equals(this);
}
if (! getClass().equals(o.getClass())) return false;
PharmacyImpl p = (PharmacyImpl) o;
// compare two PharmacyImpl's this and p
}
Also, be sure to implement hashCode() as well. It needs to return a value
which is consistent with equals() - i.e. two objects which are equals()
should have the same hashCode().
-steve
Steve Clark
ECOS Development Group
[EMAIL PROTECTED]
(970)226-9291
G�nther Wieser <[EMAIL PROTECTED]>
05/02/2005 04:15 AM
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Subject
problem with lists in n:m relation and proxy=dynamic
hi,
i've two classes that are linked to each other (bi-directional) using an
indeirection table. they are called "pharmacy" and "campaign", and
pharmacy
has a method "List getCampaigns()" to retreive all campaigns it is in, and
campaign has a method "List getPharmacies()", which gives back the list of
pharmacies that participate in this campaign.
when i need to remove one pharmacy from a campaign, i do the following:
boolean campRemoveResult = campaign.getPharmacies().remove(pharmacy);
boolean pharmRemoveResult = pharmacy.getCampaigns().remove(campaign);
then i store both of the them to have my changes persistet. i can see in
the
database that the entry in the indirection table has beem removed.
BUT: pharmRemoveResult is TRUE, but campRemoveResult = FALSE, and the list
"campaign.getPharmacies()" still contains the pharmacy i just removed.
so far i found out that the pharmacy object linked to the list in campaign
is somehow different to the pharmacy object i have during runtime. if i do
a
toString() on the pharmacy i have and the pharmacy i found in the pharmacy
list of camaign (searched for the same primary key), the both have the
same
object id and all the values AND references to other objects are the same.
still, the "equals()" method returns false.
pharmacy has "proxy=dynamic", and if i remove this, everything works fine.
but this is of course no solution for my problem.
anyone an idea how to successfully remove objects from a list if the only
object that should be removed has proxy=dynamic? am i doing something
fundamentally wrong here?
kr,
guenther
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