RFR(s): 8203670: unmodifiable List iterator() implementations should not be ListIterators

[Ivan Gerasimov]

Hi Stuart!

Out of curiosity.  What if someone does something like

if (it instanceof ListIterator) {
     // optimized for bidirectional access
} else {
     // slower algorithm
}

previous(), nextIndex() and previousIndex() methods are not declared to 
be optional, so is it appropriate to throw UnsupportedOperationException 
from them?

Someone may assume that if an object can be cast to ListIterator 
interface, non-optional methods should not throw UOE.

With kind regards,

Ivan


On 6/25/18 3:06 PM, Stuart Marks wrote:
> Hi all,
>
> Please review this small changeset that ensures that calling 
> iterator() on an unmodifiable List (from List.of, et. al.) returns an 
> instance that cannot be downcast to ListIterator and used as such.
>
> Bug:
>
>     https://bugs.openjdk.java.net/browse/JDK-8203670
>
> Webrev:
>
>     http://cr.openjdk.java.net/~smarks/reviews/8203670/webrev.0/
>
> Thanks,
>
> s'marks
>

-- 
With kind regards,
Ivan Gerasimov