JavaFX CheckBoxTableCell refuses to bind to value

Question

I have a TableView with a column that should be a checkbox for a boolean value (JavaFX 16, Java 11), but for some reason the checkbox refuses to actually bind to the field of the object. Trying to use the forTableColumn static method specifically made for boolean columns already fails, and I've tried extending CheckBoxTableColumn and making a binding inside it to no avail (though I shouldn't need to do that for just the basic binding.

In the controller of my FXML I'm calling ascColumn.setCellFactory(CheckBoxTableCell.forTableColumn(ascColumn));, with my column being

and it works of course, since the checkbox appears, but the checking and unchecking doesn't actually reach the source object. No other column needs the field to be an ObservableValue, all others can deal with it themselves, so I'm looking for a solution to doing it with the source value being just a regular boolean. I've also tried setting the selectedStateCallback to return a BooleanProperty which I then added a listener to, but the listener never gets called.

Ultimately what I want to achieve is for the checkboxes to only appear if the object of the row meets certain conditions, for which I've made a new class that extends CheckBoxTableCell, however since I can't get the default one working in the first place, I can't get that to work either, so I need to tackle this first.

EDIT: Since I guess this wasn't enough to demonstrate the problem, here's a sample.

Controller:

public class Controller {
    @FXML
    private TableColumn checkColumn;

    @FXML
    private TableView table;

    public void initialize() {
        List items = new ArrayList<>();
        items.add(new TestObject("test1", false));
        items.add(new TestObject("test2", false));
        items.add(new TestObject("test3", true));
        table.setItems(FXCollections.observableArrayList(items));
        checkColumn.setCellFactory(CheckBoxTableCell.forTableColumn(checkColumn));
    }
}

FXML:

Main class:

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }

    @Override
    public void stop() throws Exception {
        super.stop();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

build.gradle:

plugins {
    id 'java'
    id 'application'
    id 'org.openjfx.javafxplugin' version '0.0.9'
}

group 'org.example'
version '1.0-SNAPSHOT'

mainClassName = 'Main'

repositories {
    mavenCentral()
}

test {
    useJUnitPlatform()
}

javafx {
    version = "16"
    modules = [ 'javafx.controls', 'javafx.fxml' ]
}

As I said, everything else works, without needing to rely on the input values already being properties, and the doc of the forTableColumn method literally say that the column specifically has to be Boolean (not Observable), so unless I'm severely misunderstanding something, it's supposed to work

anko · Accepted Answer

[...] so I'm looking for a solution to doing it with the source value being just a regular boolean. [...]

Then you can't use CheckBoxTableCell.forTableColumn() as far as I know. You can define your own custom table cell with a CheckBox like this:

package org.example;

import javafx.application.Application;
import javafx.beans.property.SimpleObjectProperty;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

import java.util.stream.IntStream;

public class App extends Application {

    @Override
    public void start(Stage stage) {

        // Create table and column:
        TableView table = new TableView<>();

        TableColumn // Do not use  here!
                checkBoxCol = new TableColumn<>("checkBoxCol");

        table.getColumns().add(checkBoxCol);

        // Some styling:
        table.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY);
        checkBoxCol.setStyle("-fx-alignment: center;");

        // Set cell value with the use of SimpleObjectProperty:
        checkBoxCol.setCellValueFactory(cellData -> new SimpleObjectProperty<>(cellData.getValue()));

        // Create custom cell with the check box control:
        checkBoxCol.setCellFactory(tc -> new TableCell<>() {

            @Override
            protected void updateItem(Item item, boolean empty) {
                super.updateItem(item, empty);

                if (item == null || empty) {
                    setGraphic(null);
                } else {
                    CheckBox checkBox = new CheckBox();

                    // Set starting value:
                    checkBox.setSelected(item.isSelected());

                    // Add listener!!!:
                    checkBox.selectedProperty().addListener((observable, oldValue, newValue) ->
                            item.setSelected(newValue));

                    setGraphic(checkBox);
                }
            }
        });

        // Print items to see if the selected value gets updated:
        Button printBtn = new Button("Print Items");
        printBtn.setOnAction(event -> {
            System.out.println("---");
            table.getItems().forEach(System.out::println);
        });

        // Add test data:
        IntStream.range(0, 3).forEach(i -> table.getItems().add(new Item()));

        // Prepare and show stage:
        stage.setScene(new Scene(new VBox(table, printBtn), 100, 200));
        stage.show();
    }

    /**
     * Simple class with just one "regular boolean" property.
     */
    public class Item {

        private boolean selected = false;

        @Override
        public String toString() {
            return Item.class.getSimpleName()
                    + "[selected=" + selected + "]";
        }

        // Getters & Setters:
        public boolean isSelected() {
            return selected;
        }

        public void setSelected(boolean selected) {
            this.selected = selected;
        }
    }

    public static void main(String[] args) {
        launch();
    }
}

Ultimately what I want to achieve is for the checkboxes to only appear if the object of the row meets certain conditions [...]

You can then add an if-condition in the updateItem() method like e. g.:

                [...]
                if (item == null || empty) {
                    setGraphic(null);
                } else {
                    if (showCheckBox) {
                        CheckBox checkBox = new CheckBox();
                        [...]
                        setGraphic(checkBox);
                    } else
                        setGraphic(null);
                }
                [...]

But I think it is best to work with observable properties. If you don't want to touch the original class, you can maybe create a wrapper class.

JavaFX CheckBoxTableCell refuses to bind to value

Answers (1)

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