Re: [Springframework-developer] Comparator singletons MIA?

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Well, depends on whether one consider NullSafeComparator as a plain
decorator. Arguably NullSafeComparator is most useful for Comparables. =
The
primary point of the class is to compare Comparables in a null-safe =
fashion.

ComparableComparator on the other hand is really just a plain adapter
between Comparator and Comparable, without any value-add. It's mainly =
useful
as internal adapter, not so much for plain direct usage.

You would hardly ever use ComparableComparator directly for sorting or =
the
like. You would rather simply rely on "natural" sort order, i.e. =
Comparable
directly. E.g. "Collections.sort(List, Comparator)" vs
"Collections.sort(List)".

Juergen
=20

-----Original Message-----
From: spr...@li...
[mailto:spr...@li...] On Behalf =
Of
Oliver Hutchison
Sent: Friday, July 22, 2005 10:49 AM
To: spr...@li...
Subject: RE: [Springframework-developer] Comparator singletons MIA?

Ahhh....

Don't these really belong in ComparableComparator? Given that they would
mostly compare Comparables? To be honest I wouldn't even think to look =
in
NullSafeComparator for a ComparableComparator.

But I can live with it ;-)

Thanks,

Ollie

> -----Original Message-----
> From: spr...@li...
> [mailto:spr...@li...]
>  On Behalf Of Juergen Hoeller
> Sent: Friday, 22 July 2005 6:12 PM
> To: spr...@li...
> Subject: Re: [Springframework-developer] Comparator singletons MIA?
>=20
> NullSafeComparator has two such singletons: NULLS_LOW and NULLS_HIGH,=20
> each using a ComparableComparator underneath. I guess you could simply =

> use those singletons rather than one on ComparableComparator itself.
>=20
> Juergen
> =20
>=20
> -----Original Message-----
> From: spr...@li...
> [mailto:spr...@li...]
>  On Behalf Of Oliver Hutchison
> Sent: Friday, July 22, 2005 4:22 AM
> To: spr...@li...
> Subject: RE: [Springframework-developer] Comparator singletons MIA?
>=20
> Actually I see this is only the case for ComparableComparator (I've=20
> got to many versions of the code open at the moment) the=20
> NullSafeComparator and BooleanComparator singletons are still there.
>=20
> My question still stands through.=20
>=20
> Oliver
>=20
> > -----Original Message-----
> > From: spr...@li...
> > [mailto:spr...@li...]
> >  On Behalf Of Oliver Hutchison
> > Sent: Friday, 22 July 2005 10:32 AM
> > To: spr...@li...
> > Subject: [Springframework-developer] Comparator singletons MIA?
> >=20
> > Jurgen,
> >=20
> > I've just started upgrading Spring Rich to the latest
> spring code base
> > and noticed that all of the Comparator singletons (which
> Spring Rich
> > uses a lot) in the o.s.util.comparator package have been removed.
> >=20
> > These classes are IMHO perfect examples of where you should
> be using a
> > singleton. Given that every instance will exhibit exactly the same=20
> > behaviour, why would you ever want to have more that one
> instance of a
> > class like ComparableComparator?
> > Also how much cleaner is this:
> >=20
> > ComparableComparator.nullSafeInstance().compare(argument1,
> argument2)
> >=20
> > to this?
> >=20
> > new NullSafeComparator(new ComparableComparator(),=20
> > true).compare(argument1, argument2)
> >=20
> > and more performant to boot.
> >=20
> > Anyway, obviously I can live without them, but I'm curious
> about the
> > rational behind the removal?
> >=20
> > Thanks,
> >=20
> > Oliver
> >=20
> >=20
> >=20
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