Russ Kepler <[email protected]> wrote on 11/08/2012 09:22:41 AM:
> From: Russ Kepler <[email protected]>
> To: Tomcat Users List <[email protected]>,
> Date: 11/08/2012 09:23 AM
> Subject: Re: This is just plain ... odd.
>
> On Thursday, November 08, 2012 01:35:55 PM Lyallex wrote:
> > I have tried everything I can think of to reproduce this behaviour
> > in a standalone Java program but the list is always returned
> > as required. When I call the method from a servlet the list is always
> > returned
> > in it's natural order, I know collections.sort is being executed as
> > the list is in alpha order, it's almost as if the comparator is being
> > replaced in some way
> >
> > I have no servlet filters or any other code 'in the way' between the
facade
> > and the initialization servlet.
> >
> > Any ideas ?
> I'm not sure that you can ever get consistent results if the input order
is
> random. The Collections.sort() implements a merge sort and the merge
sort
> depends on a consistent result from the compare() method. As
implemented the
> compare() will return what you want when the object being compared
against is
> the "Misc" object but return a string compare when it isn't. Try this:
> @Override
> public int compareTo(Category c) {
> if(category.equals("Miscellaneous")){
> return 1;
> } elseif (c.category.equals("Miscellaneous")) {
> return -1;
> else{
> return category.compareTo(c.category);
> }
> }
> (side comment: If the list is a decent size it might make sense to
compare
> against the Misc object rather than compare all strings but it's likely
not
> worth the bother).
> The was I usually handle this is to .remove the offending object
> from the list,
> sort, then .add it back on after the sort. Keep the odd code local to
the
> oddity.
This is closer, but still doesn't work correctly if two "Misc" categories
are being compared, or one "Misc" category is compared to itself.
Try:
@Override
public int compareTo(Category c) {
if(category.equals("Miscellaneous")) {
if(category.equals(c.category) return 0; // correctly
handle equality.
else return 1;
} elseif (c.category.equals("Miscellaneous")) {
return -1;
} else {
return category.compareTo(c.category);
}
}
---------------------------------------------------
David S. Johnson
DeskNet Inc.
