RFR: 8091429: ObservableList<E>#setAll(int from, int to, Collection<? extends E> col) [v2]
Kevin Rushforth
kcr at openjdk.org
Wed Oct 29 17:28:41 UTC 2025
On Mon, 20 Oct 2025 05:06:20 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:
>> This PR implements two new default methods on `ObservableList` to be able to replace elements at a given position or within a specified range.
>>
>> Justification for this change is to allow an `ObservableList` to be bulk modified resulting in a single `ListChangeListener` call back. In this way the callbacks don't observe the list changing its size from S to S-X back to S again(*). Currently the only way to bulk replace a range of items is to remove X items then add X items, resulting in two listener callbacks in between which the size of the list can be observed to change.
>>
>> The other alternative is to call `set` individually for each item, which results in many change notifications.
>>
>> With the addition of this PR, and the changes in `ModifiableObservableListBase`, replacing a range of items becomes a single change callback.
>>
>> (*) The list may indeed change size still as plain `List` does not have `setAll` operations; size listeners may observe this, but it will no longer be observable from a `ListChangeListener` due to multiple separate callbacks.
>
> John Hendrikx has updated the pull request incrementally with two additional commits since the last revision:
>
> - Fix test
> - Rename setAll to replaceRange and removed superfluous method
I can review this.
@hjohn If you're happy with the current `replaceRange` name (which seems good to me), can you update the JBS and PR title to reflect this?
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PR Comment: https://git.openjdk.org/jfx/pull/1937#issuecomment-3462788655
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