String.contains(CharSequence) calls toString on argument

[Vitaly Davidovich]

>
> If CharSequence is mutable and thread-safe, I would expect toString()
> implementation to provide the atomic snapshot (e.g. do the
> synchronization). Therefore, I find Sherman's argument interesting.


That's my point about "it ought to be up to the caller" -- they're in a
position to make this call, but String.contains() is playing defensive
because it has no clue of the context.

On Fri, Mar 20, 2015 at 11:55 AM, Aleksey Shipilev <
aleksey.shipilev at oracle.com> wrote:

> If CharSequence is mutable and thread-safe, I would expect toString()
> implementation to provide the atomic snapshot (e.g. do the
> synchronization). Therefore, I find Sherman's argument interesting.
>
> On the other hand, we don't seem to be having any details/requirements
> for contains(CharSequence) w.r.t. it's own argument. What if
> String.contains pulls the values one charAt at a time? The concurrency
> requirements are not enforceable in CharSequence alone then, unless you
> call the supposed-to-be-atomic toString() first.
>
> -Aleksey.
>
> On 03/20/2015 06:48 PM, Vitaly Davidovich wrote:
> > Yes, but that ought to be for the caller to decide.  Also, although the
> > resulting String is immutable, toString() itself may observe mutation.
> >
> > On Fri, Mar 20, 2015 at 11:40 AM, Xueming Shen <xueming.shen at oracle.com>
> > wrote:
> >
> >> On 03/20/2015 02:34 AM, Tomasz Kowalczewski wrote:
> >>
> >>> Hello!
> >>>
> >>> Current implementation of String.contains that accepts CharSequence
> calls
> >>> toString on it and passes resulting string to indexOf(String). This IMO
> >>> defeats the purpose of using CharSequences (that is to have a mutable
> >>> character buffer and not allocate unnecessary objects).
> >>>
> >>>
> >> It is arguable that cs.toString() may serve the purpose of taking a
> >> snapshot of an otherwise
> >> "mutable" character buffer?
> >>
> >> -Sherman
> >>
> >>
> >>  Is changing this a desirable development? It seems pretty
> straightforward
> >>> to port indexOf(String) to use CharSequence.
> >>>
> >>> If all you need is patch then I can work on it (I have signed OCA) just
> >>> wanted to make sure it is not a futile work.
> >>>
> >>>
> >>
> >>
>
>
>