Didn't look too deep, but seems like a bug or incorrect doc. I don't see
such specifications in other "setOnX" methods.
On Sun, May 28, 2023 at 1:02 PM John Hendrikx <john.hendr...@gmail.com>
wrote:
> When looking at the code for Scene#setOnKeyPressed, I noticed that it
> calls Scene#setEventHandler. This is documented as:
>
> /**
> * Sets the handler to use for this event type. There can only be
> one such
> * handler specified at a time. This handler is guaranteed to be
> called
> * first. This is used for registering the user-defined onFoo event
> * handlers.
> *
> * @param <T> the specific event class of the handler
> * @param eventType the event type to associate with the given
> eventHandler
> * @param eventHandler the handler to register, or null to unregister
> * @throws NullPointerException if the event type is null
> */
> protected final <T extends Event> void setEventHandler(
> final EventType<T> eventType,
> final EventHandler<? super T> eventHandler) {
>
> Note that it specifically says "This handler is guaranteed to be called
> first."
>
> This function eventualy calls CompositeEventHandler#setEventHandler.
> This class tracks a chain of handlers, and reserves a special spot for a
> single special "eventHandler". Yet, in its dispatchBubblingEvent
> method, it clearly calls the "special" handler LAST... see below:
>
> public void dispatchBubblingEvent(final Event event) {
> final T specificEvent = (T) event;
>
> EventProcessorRecord<T> record = firstRecord;
> while (record != null) {
> if (record.isDisconnected()) {
> remove(record);
> } else {
> record.handleBubblingEvent(specificEvent);
> }
> record = record.nextRecord;
> }
>
> if (eventHandler != null) {
> eventHandler.handle(specificEvent);
> }
> }
>
> I've confirmed this with this small program (order of calls doesn't make
> a difference):
>
> public static class App extends Application {
> @Override
> public void start(Stage primaryStage) {
> Button button1 = new Button("111");
>
> HBox hBox = new HBox();
> hBox.getChildren().addAll(button1);
> Scene scene = new Scene(hBox, 300, 300);
>
> scene.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
> System.out.println("KeyPressedHandler " + e);
> });
> scene.setOnKeyPressed(e -> {
> System.out.println("Main " + e);
> e.consume();
> });
>
> primaryStage.setScene(scene);
> primaryStage.show();
> }
>
> Which outputs the events not in the order documented:
>
> KeyPressedHandler KeyEvent [source = javafx.scene.Scene@36dbf594, target
> = Button@5dd3d27e[styleClass=button]'111', eventType = KEY_PRESSED,
> consumed = false, character = , text = f, code = F]
> Main KeyEvent [source = javafx.scene.Scene@36dbf594, target =
> Button@5dd3d27e[styleClass=button]'111', eventType = KEY_PRESSED,
> consumed = false, character = , text = f, code = F]
>
> --John
>
>
