Impact of code difference in Collection#contains() worth improving?

[Ulf Zibis]

Am 28.08.2014 um 19:30 schrieb Louis Wasserman:
> Comparator is spec'd to be allowed to return any number, positive, negative, or zero, but indexOf 
> is specifically spec'd to return -1.

Yes, I know. I wanted to say, that from this knowing some developer might assume the same for 
indexOf when successfully using ArrayList at contains() with other negative value than -1.

> If an indexOf method returns a negative value other than -1, that is a bug;

Yes, but how you suggest to deal with such a bug in existing code. If we would unify JDK code to 
LinkedList style, it would break such existing code. That's what I wanted to point on.

Does the original thread opener want to open a bug e.g. "Unify code of contains()"?
If not, the discussion doesn't make sense anymore.

-Ulf


>
>
> On Thu, Aug 28, 2014 at 10:27 AM, Ulf Zibis <Ulf.Zibis at cosoco.de <mailto:Ulf.Zibis at cosoco.de>> wrote:
>
>
>     Am 27.08.2014 um 17:51 schrieb Martin Buchholz:
>
>         The ArrayList version saves one byte of bytecode, and is therefore very
>         slightly better.  We should bless that version and use it consistently.
>
>
>     +1
>     Additional argument:
>     The LinkedList code requires to load 32/64-Bit -1 into CPU. This may take some time on some
>     CPU and at least wastes memory footprint.
>     Additionally register pressure increases.
>     Vitaly, please correct me, if I'm wrong, just for learning more.
>
>     Another advantage is that there is no problem if some implementation of indexOf() erroneously
>     returns another negative value than -1. I remember some compare() implementations, which
>     sometimes return different values than only -1, 0, +1.
>
>     -Ulf
>
>
>             ArrayList:
>
>                  public boolean contains(Object o) {
>                      return indexOf(o) >= 0;
>                  }
>
>             LinkedList:
>
>                  public boolean contains(Object o) {
>                      return indexOf(o) != -1;
>                  }
>
>
>
>
>
> -- 
> Louis Wasserman