On Thu, 24 Mar 2022 16:44:50 GMT, XenoAmess <[email protected]> wrote:
>> src/java.base/share/classes/java/util/HashMap.java line 2556:
>>
>>> 2554: */
>>> 2555: static int calculateHashMapCapacity(int expectedSize) {
>>> 2556: if (expectedSize >= 1610612736) {
>>
>> It would be clearer with a comment on the constant or use the expression
>> (the compiler will evaluate it).
>> `Integer.MAX_VALUE / 4 * 3`.
>>
>> There also might be a valid point to make about a fail-fast exception if the
>> requested capacity cannot be achieved. If defaulted to MAX_VALUE, the
>> application would start populating the map and then at some later point get
>> an exception when it cannot be resized to accommodate the n+1'th item.
>
>> It would be clearer with a comment on the constant or use the expression
>> (the compiler will evaluate it). `Integer.MAX_VALUE / 4 * 3`.
>
> @RogerRiggs
>
> No, as `Integer.MAX_VALUE / 4 * 3` is actually 1610612733,
>
> and `(int)Math.ceil(1610612733/0.75)` is actually 2147483644,
>
> while `Integer.MAX_VALUE` is 2147483647
>
> Although in this situation 2147483644 and 2147483647 is same (both would be
> trimed down to 1073741824 when enter the HashMap constructor), but I think it
> be better to be more precise.
>
> However if you want me to change it to `expectedSize >= Integer.MAX_VALUE / 4
> * 3 + 3`, then I think it acceptable, but looks a little weird.
>
> So should we change it to `expectedSize >= Integer.MAX_VALUE / 4 * 3 + 3`?
> There also might be a valid point to make about a fail-fast exception if the
> requested capacity cannot be achieved. If defaulted to MAX_VALUE, the
> application would start populating the map and then at some later point get
> an exception when it cannot be resized to accommodate the n+1'th item.
@RogerRiggs
No, as I want 100% same reaction to use these functions like using new
HashMap(int)
So as the HashMap constructor itself doesn't throw exception when oversize,
this function shall neither.
-------------
PR: https://git.openjdk.java.net/jdk/pull/7928
