[jfx19] RFR: 8290331 Binding value left null when immediately revalidated in invalidation listener

[Michael Strauß]

On Thu, 14 Jul 2022 23:37:31 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

> I introduced a bug with the fluent bindings PR which affects all ObjectBindings.
> 
> This is the code that fails:
> 
>         SimpleObjectProperty<Boolean> condition = new SimpleObjectProperty<>(true);
>         ObservableValue<String> binding = condition.map(Object::toString);
> 
>         binding.addListener(o -> { binding.getValue(); });
> 
>         condition.set(false);
> 
>         assertEquals(false, binding.getValue());  // returns null (!)
> 
> This PR fixes this problem and adds a test case to cover it.

modules/javafx.base/src/main/java/javafx/beans/binding/ObjectBinding.java line 184:

> 182:             ExpressionHelper.fireValueChangedEvent(helper);
> 183: 
> 184:             if (!valid) {  // if still invalid after calling listeners...

On a personal note: I think implementation comments are best presented as a block, and not describing individual lines of code. That makes it a bit easier for future authors to work with the code. But that's just my two cents 😊

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PR: https://git.openjdk.org/jfx/pull/829