RFR : 7144488 StackOverflowError occurres on list via Collections.synchronizedList(List)

David Holmes david.holmes at oracle.com
Thu Feb 23 09:56:58 UTC 2012

On 23/02/2012 7:55 PM, Alan Bateman wrote:
> On 23/02/2012 02:44, David Holmes wrote:
>> All of the SynchronizedX.equals methods should be fixed ie
>> SynchronizedSet, SynchronizedList and SynchronizedMap. It should
>> always be valid to ask if a.equals(a). The idiomatic form used
>> elsewhere (CheckedXXX) is:
>> public boolean equals(Object o) { return o == this || list.equals(o); }
>> I'm not a fan of collections containing themselves, but I think it is
>> simple to fix contains(o)/contains[Key]|[Value](o) and remove(o) in a
>> similar way. Though none of the wrapped collections currently handle
>> that case, so I'm okay with not addressing this part.
>> I don't see the recursion potential in hashCode() in the wrappers.
> The hashCode of a Set requires summing the hash codes of each of the
> elements so it can't work for the case that a set contains itself.

Right, but that's a general problem with collections, not with the 
wrappers specifically.


> Anyway, I think the best we can do it to have the equals methods use the
> above form. I wasn't aware of the warning in List that Sean pointed out
> and maybe there should be similar warnings elsewhere.
> -Alan

More information about the core-libs-dev mailing list