Equals method and collections

magic · **Posted:** Mon Feb 14, 2005 10:14 am

Hibernate version: Hibernate3 beta4b

Mapping documents:

Code:

    <bag name="phoneNumbers" table="phone" cascade="all-delete-orphan">
      <key column="msl_id" not-null="true"/>
      <element column="pho_phone" type="string" length="255" not-null="true"/>
    </bag>

Code between sessionFactory.openSession() and session.close():

Code:

(snip)
            ses.addPhoneNumber("+33 123456789 (Me)");
            ses.addPhoneNumber("+33 123456789 (You)");
            ses.addPhoneNumber("+33 123456789 (Other)");
            assertEquals(ses.getEmails().size(),2);
(snip)
            hSession.clear();

            transaction = hSession.beginTransaction();
            storedSes = (Session)hSession.load(Session.class, ses.getSQLId());
            assertNotNull(storedSes);
            assertEquals(ses.getPhoneNumbers(), storedSes.getPhoneNumbers());

Why ses.getPhoneNumbers().equals(storedSes.getPhoneNumbers()) returns false ?

Code:

    public Collection<String> getPhoneNumbers() {
        return this.phoneNumbers;
    }

emmanuel · **Posted:** Mon Feb 14, 2005 11:34 am

year, I had this discussion before with Gavin... and failed to convince it :-)
We choose not to respect the Collection semantic for Bags since it implies loading the full collections to correctly implement it.
It is a bad practice to compare collections, anyway.

Since Bag is now the base implementation of our EJB3 API, I would be incline to fix it... if I figure how to convince Gavin

magic · **Posted:** Mon Feb 14, 2005 11:41 am

emmanuel wrote:

year, I had this discussion before with Gavin... and failed to convince it :-)
We choose not to respect the Collection semantic for Bags since it implies loading the full collections to correctly implement it.

Ok... so.. if i use list, that will work ? :)

emmanuel wrote:

It is a bad practice to compare collections, anyway.

Why ? (i'm not a java guru) I missed a specification ?
To me, 2 collections are equals if all elements are 'equals', aren't ?

emmanuel wrote:

Since Bag is now the base implementation of our EJB3 API, I would be incline to fix it... if I figure how to convince Gavin

Good luck ;-)

emmanuel · **Posted:** Mon Feb 14, 2005 11:54 am

Everything but Bags will work.

What is you particular use case for doing such mass comparison in a ORM environment?

magic · **Posted:** Mon Feb 14, 2005 12:00 pm

emmanuel wrote:

Everything but Bags will work.

What is you particular use case for doing such mass comparison in a ORM environment?

I just tested, i prepared some JUnit test case, and assertEquals failed. So, i wanted know why :) I've no particular use case for the moment. I like understand :)