Bug in ArrayList iterator

[Mario Torre]

2015-01-07 12:22 GMT+01:00 Stanislav Baiduzhyi <sbaiduzh at redhat.com>:
> On Wednesday 07 January 2015 11:20:57 you wrote:
>> On 07/01/15 10:57, Stanislav Baiduzhyi wrote:
>> > On Wednesday 07 January 2015 10:56:01 Chris Hegarty wrote:
>> >>            public boolean hasNext() {
>> >>
>> >> -            return cursor != size;
>> >> +            return cursor != itrSize;
>> >>
>> >>            }
>> >
>> > If the user will invoke list.remove(E) to remove current or previous
>> > element then iterator will be skipping some elements.
>>
>> If this happens, then next() and/or remove() will throw CME.
>>
>>   Throwing ConcurrentModification
>>
>> > in hasNext() looks better in such case.
>>
>> It is not clear to me that users would be expecting CME from hasNext(),
>> whereas it is more next() and remove() is more obvious.
>
> Yes, but that exactly how it works now, that's why second invocation of
> hasNext() returns false and we can see the issue Remi is talking about. If
> hasNext() will be throwing ConcurrentModification than will work as early
> warning system that something is wrong with this iterator.

But hasNext isn't modifying things, why should it throw
ConcurrentModification? I would find it very confusing, and also
likely non backward compatible.

Cheers,
Mario

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