CODEWITHSUNDEEP
javafxbindingobservable
mr mcwolf
mr mcwolf

Reputation: 2859

Create BooleanBinding binded with List/ObstableList values

I'm trying to create BooleanBinding which is a binded with Button#disableProperty(). My purpose is to enable/disable the OK button when changing a TextField from a dynamically created list of panels.

This is the initialization of the list of panels (propertiesList)

<DialogPane prefWidth="900" prefHeight="600" xmlns="http://javafx.com/javafx/8.0.172-ea" xmlns:fx="http://javafx.com/fxml/1">

    <fx:define>
        <FXCollections fx:id="propertiesList" fx:factory="observableArrayList">
            <DatabasePane name="База данни"/>
            <DatabasePane name="База данни 2"/>
        </FXCollections>
    </fx:define>

    ....

    <buttonTypes>
        <ButtonType fx:id="okButtonType" buttonData="OK_DONE" text="Готово" />
        <ButtonType buttonData="CANCEL_CLOSE" text="Затвори" />
    </buttonTypes>

</DialogPane>

Each DatabasePane contains BooleanProperty named change and corresponding getters and setters.

In the controller, I create a BooleanProperty collection from the properties of the panels added in propertiesList

List<BooleanProperty> list = propertiesList.stream()
    .map(pane -> pane.changeProperty())
    .collect(Collectors.toList());

BooleanBinding change = Bindings.createBooleanBinding(() -> true, (BooleanProperty[]) list.toArray());

Button button = (Button) dialogPane.lookupButton(okButtonType);
button.disableProperty().bind(change.not());

java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class [Ljavafx.beans.property.BooleanProperty; ([Ljava.lang.Object; is in module java.base of loader 'bootstrap'; [Ljavafx.beans.property.BooleanProperty; is in module javafx.base of loader 'app')

If I use ObservableList there are no errors, but only changes are made to the list itself

ObservableList<BooleanProperty> list = propertiesList.stream()
    .map(pane -> pane.changeProperty())
    .collect(Collectors.toCollection(() -> FXCollections.observableArrayList()));

BooleanBinding change = Bindings.createBooleanBinding(() -> true, list);

Button button = (Button) dialogPane.lookupButton(okButtonType);
button.disableProperty().bind(change.not());

Upvotes: 1

Views: 869

Answers (1)

fabian
fabian

Reputation: 82491

List.toArray() returns an Object[] array not an BooleanProperty[] array, but you cast the object array to BooleanProperty here:

(BooleanProperty[]) list.toArray()

I recommend using Stream's toArray method taking a IntFunction:

Observable[] dependencies = propertiesList.stream()
                                          .map(DatabasePane::changeProperty)
                                          .toArray(Observable[]::new);

BooleanBinding change = Bindings.createBooleanBinding(() -> true, dependencies);

Unless you change the Callable<Boolean> to something more meaningfull though, you could leave out the dependencies as well, since the binding never contains a value but true.

BooleanBinding change = Bindings.createBooleanBinding(() -> true, list);

does not work, since the list itself implements Observable so you're passing a array containing only the list to the varargs parameter, i.e. it's equivalent to

BooleanBinding change = Bindings.createBooleanBinding(() -> true, new Observable []{ list });

and the only InvalidationListener that is added is added to the list itself, not to it's contents.

Upvotes: 2

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