If anyone decides to write in this functionality, and is willing to make
it available..I think it would be very useful.
MD
Gary Gregory wrote:
> You could try using the EqualsBuilder class from the Apache Jakarta
> Commons Lang project. See
> http://jakarta.apache.org/commons/lang/api/org/apache/commons/lang/builder/EqualsBuilder.html
>
> Gary
>
> -----Original Message-----
> From: Mattias R?nnblom [mailto:mattias.ronnblom_at_ericsson.com]
> Sent: Tuesday, January 28, 2003 2:28 AM
> To: JAXB-INTEREST_at_JAVA.SUN.COM
> Subject: JAXB and equals
>
>
> Hi,
>
> I asked jaxb-comments why the equals() method only has the default
> implementation (in Object, only object equality), and not, which
> I would have expected, an implementation comparing each attribute
> using equals() down the object graph.
>
> I got the answer that it's hard to implement, and that there were
> some performance issues. The thread on this list with the subject
> "hashCode" seems to end with the same answer.
>
> But why is it hard to implement? And what are the performance issues?
> Putting these objects in a Map will be slower, as hashCode() will be
> more expensive. Is there something else that will be slower? Off
> course, equals() will be slower, but if you need compare the value
> of the objects you need to compare the value of the objects. If
> you don't you probably better off using ==. And if equals/hashCode
> only is generated if the user asks for it, off by default, you can
> take the performance hit only if you need to have value-based semantics
> in equals().
>
> After all, what's being generated is Data Transfer Objects (aka Value
> Objects), and (god forgive) have no behaviour, then a equals()
> with value-based semantics would be what most people expects.
>
> What workaround are available? Hand coded equals (one per generated
> class) will be tidious and error-prone, and will duplicate
> knowledge already present in the XSD files (and will reintroduce
> one the of the problems that JAXB originally tries to solve, as
> far as I see). As the classes are JavaBeans, I guess one could
> write a generic equals(), using reflection? Or should I unmarshal
> both objects and compare the strings?
>
> Is there some way to force the generated classes to subclass from
> some class? That would be handy if you could find some clean way to
> write a generic equals().
>
> Kind regards,
> Mattias
>