RFR: 8091429: ObservableList<E>#setAll(int from, int to, Collection<? extends E> col) [v2]

[John Hendrikx]

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

With this modification, two lists can be kept in sync with each other with this minimal code, and with minimal notifications:

    change -> {
      while(change.next()) {
        int from = change.getFrom();
        int to = change.getTo();

        if(change.wasPermutated()) {
          destination.replaceRange(from, to, change.getList().subList(from, to).stream().map(mapper).toList());
        }
        else {
          int removed = change.getRemovedSize();

          destination.replaceRange(from, from + removed, change.getList().subList(from, to).stream().map(mapper).toList());
        }
      }
    };

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PR Comment: https://git.openjdk.org/jfx/pull/1937#issuecomment-3420726920