> This PR creates a WeakReferenceWrapper object to replace direct uses of > WeakReference in controls where the referent is a user-supplied object of an > unknown type. > > As noted in JEP 401, which is now integrated into JDK 28, "The garbage > collection APIs in java.lang.ref ... do not allow developers to manually > manage value objects in the heap. Attempts to create Reference objects for > value objects throw IdentityException at run time." > > Several core JDK classes such as all of the primitive wrappers (e.g., > `Integer`, `Character`), `Optional`, `LocalDateTime`, and a few others are > now value types if JDK 28 is run with the `--enable-preview` option. > > The `ListView`, `ComboBox`, `TableView`, and `TreeTableView` controls take a > parameterized item type and hold items of that type. The following places in > the implementation create weak references to an item. If that item type is a > value class -- meaning that it does not have identity -- creating the > `WeakReference` fails. > > As noted in the JBS issue, there are 3 cases to consider. > > 1. `SelectedItemsReadOnlyObservableList<E>` -- `E` is the item type (created > by `MultipleSelectionModelBase<T>`) : `ListView`, `TableView`, `ComboBox` > (due to its skin creating a `ListView<T>`) -- replace with > `WeakReferenceWrapper` > > 2. `TablePosition<S,T>` -- `S` is the item type : `TableView` -- the > reference is unused, so I removed it > > 3. `TableCell<S,T>` and `TreeTableCell<S,T>` -- `S` is the item type : > `TableView`, `TreeTableView` -- replace with `WeakReferenceWrapper` > > The new `WeakReferenceWrapper` class takes a referent of any type and either > creates a WeakReference (if it has identity) or directly stores the reference > (if it is null or does not have identity). I added a test for the wrapper. > > All of the controls tests pass with this fix. I did three test runs as > follows: > > 1. JDK 25 > 2. JDK 28 without `--enable-preview` > 3. JDK 28 with `--enable-preview` > > Without the fix, 31 controls tests fails on the 3rd run. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai).
Kevin Rushforth has updated the pull request incrementally with one additional commit since the last revision: document that WeakReferenceWrapper might be modified or eliminated in the future ------------- Changes: - all: https://git.openjdk.org/jfx/pull/2250/files - new: https://git.openjdk.org/jfx/pull/2250/files/56a17b10..68fd3de7 Webrevs: - full: https://webrevs.openjdk.org/?repo=jfx&pr=2250&range=01 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=2250&range=00-01 Stats: 16 lines in 1 file changed: 16 ins; 0 del; 0 mod Patch: https://git.openjdk.org/jfx/pull/2250.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/2250/head:pull/2250 PR: https://git.openjdk.org/jfx/pull/2250
