On 22/05/2013 2:51 AM, Jason Mehrens wrote:
Aleksej,
Actually, the readObject calls the super.initCause, because there is no
initCause in XPathException.
I would think that subclasses of XPE will see calls to this.initCause from
readObject. That wouldn't have happened prior to this change.
I think this is why super.initCause() (or super.getCause()) must be
called here. If you invoke this.xxx() then you may well be invoking a
subclass specialization and you don't know what it will do.
About 'super.getCause() == null' check: yes it can be done in such way.
In current version I caught the IllegalStateException to correctly
process the situation when the cause was already initialized.
I think you'll always have to catch ISE. If super.getCause is not null you know
initCause will fail. I would think it would be cheaper to null check than to
fillStackTrace. But, I haven't tested that.
I think readObject only needs to account for deserializing an older
version of the exception which will have a non-null local cause, but
Throwable.cause is null. That should be rare. The common case would be
deserializing the new form, in which case initCause would fail. So I
agree with Jason that checking super.getCause() is more efficient than
always calling initCause.
David
Jason
