On Mon, 20 Oct 2025 05:06:20 GMT, John Hendrikx <[email protected]> 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());
}
}
};
-------------
PR Comment: https://git.openjdk.org/jfx/pull/1937#issuecomment-3420726920
