How to add button in JavaFX table view

Question

I have searched at Google and Stackoverflow for this and I just don't get the given examples. Can someone please explain it to me.

I want to add a button to the last column of a table view and when it gets clicked it should trigger a listener and pass the object of the buttons row. I just do not get the following example from gist.github.com:

This is my full current code:

public class SchermdeelWerkplaats extends BorderPane{

    //ATD moeder klasse met alle collecties etc.
    private ATD $;

    TableView tabel = new TableView();
    Button nieuwTaak = new Button("Nieuwe taak inboeken");
    final ObservableList<Task> data = FXCollections.observableArrayList();

    public SchermdeelWerkplaats(ATD a) {

        $ = a;

        data.addAll($.agenda);

        tabel.setEditable(false);
        tabel.setPlaceholder(new Label("Geen taken"));

        TableColumn c1 = new TableColumn("datum");
        c1.setMinWidth(200);
        TableColumn c2 = new TableColumn("type");
        c2.setMinWidth(100);
        TableColumn c3 = new TableColumn("uren");
        c3.setMinWidth(100);
        TableColumn c4 = new TableColumn("klaar");
        c4.setMinWidth(200);
        TableColumn c5 = new TableColumn("Werknemer");
        c5.setMinWidth(100);
        TableColumn c6= new TableColumn("Auto");
        c6.setMinWidth(400);
        TableColumn c7= new TableColumn("Actie");
        c7.setMinWidth(400);

        TableColumn col_action = new TableColumn<>("Action");

        col_action.setCellValueFactory(
                new Callback<TableColumn.CellDataFeatures<Task, Boolean>, 
                ObservableValue<Boolean>>() {

            @Override
            public ObservableValue<Boolean> call(TableColumn.CellDataFeatures<Task, Boolean> p) {
                return new SimpleBooleanProperty(p.getValue() != null);
            }
        });

        col_action.setCellFactory(
            new Callback<TableColumn<Task, Task>, TableCell<Task, Task>>() {

                @Override
                public TableCell<Task, Task> call(TableColumn<Task, Task> p) {
                    return new ButtonCell();
                }
            }
        );

        c1.setCellValueFactory(
            new PropertyValueFactory<Task,Date>("date")
        );
        c2.setCellValueFactory(
            new PropertyValueFactory<Task,Task.TaskType>("type")
        );
        c3.setCellValueFactory(
            new PropertyValueFactory<Task,Double>("hours")
        );
        c4.setCellValueFactory(
            new PropertyValueFactory<Task,Boolean>("done")
        );
        c5.setCellValueFactory(
            new PropertyValueFactory<Task,Employee>("employee")
        );
        c6.setCellValueFactory(
            new PropertyValueFactory<Task,Car>("car")
        );

        tabel.getColumns().addAll(c1, c2, c3, c4, c5, c6, c7);
        tabel.setItems(data);

        setCenter(tabel);
        setBottom(nieuwTaak);

    }

    //letterlijk van internet geplukt en datatype aangepast
    private class ButtonCell extends TableCell<Task, Task> {


        private Button cellButton;

        ButtonCell(){
              cellButton = new Button("jjhjhjh");
            cellButton.setOnAction(new EventHandler<ActionEvent>(){

                @Override
                public void handle(ActionEvent t) {
                    // do something when button clicked
                    Task record = getItem();
                    // do something with record....
                }
            });
        }

        //Display button if the row is not empty
        @Override
        protected void updateItem(Task record, boolean empty) {
            super.updateItem(record, empty);
            if(!empty){
                cellButton.setText("Something with "+record);
                setGraphic(cellButton);
            } else {
                setGraphic(null);
            }
        }
    }

}

Now the part where I have to create a ButtonCell extends TableCell is understandable. But how to assign this to the column?

I understand this:

c1.setCellValueFactory(
        new PropertyValueFactory<Task,Date>("date")
    );

But not this:

           TableColumn col_action = new TableColumn<>("Action");

            col_action.setCellValueFactory(
                    new Callback<TableColumn.CellDataFeatures<Task, Boolean>, 
                    ObservableValue<Boolean>>() {

                @Override
                public ObservableValue<Boolean> call(TableColumn.CellDataFeatures<Task, Boolean> p) {
                    return new SimpleBooleanProperty(p.getValue() != null);
                }
            });

            col_action.setCellFactory(
                new Callback<TableColumn<Task, Task>, TableCell<Task, Task>>() {

                    @Override
                    public TableCell<Task, Task> call(TableColumn<Task, Task> p) {
                        return new ButtonCell();
                    }
                }
            );

Answer 1

Here is my example using awesome Java 8 Functionality and extending TableCell class.

Let me give a quick explanation of what I am doing: I created a ActionButtonTableCell class that extends TableCell. And then you can use java 8 lamda functions to create an Action for the button.

import java.util.function.Function;
import javafx.event.ActionEvent;
import javafx.scene.control.Button;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.util.Callback;

public class ActionButtonTableCell<S> extends TableCell<S, Button> {

    private final Button actionButton;

    public ActionButtonTableCell(String label, Function< S, S> function) {
        this.getStyleClass().add("action-button-table-cell");

        this.actionButton = new Button(label);
        this.actionButton.setOnAction((ActionEvent e) -> {
            function.apply(getCurrentItem());
        });
        this.actionButton.setMaxWidth(Double.MAX_VALUE);
    }

    public S getCurrentItem() {
        return (S) getTableView().getItems().get(getIndex());
    }

    public static <S> Callback<TableColumn<S, Button>, TableCell<S, Button>> forTableColumn(String label, Function< S, S> function) {
        return param -> new ActionButtonTableCell<>(label, function);
    }

    @Override
    public void updateItem(Button item, boolean empty) {
        super.updateItem(item, empty);

        if (empty) {
            setGraphic(null);
        } else {                
            setGraphic(actionButton);
        }
    }
}

The implementation is then as simple as this, This is a sample button to remove the item from the table:

column.setCellFactory(ActionButtonTableCell.<Person>forTableColumn("Remove", (Person p) -> {
    table.getItems().remove(p);
    return p;
}));

Update based on comments: While the approach of using a Button within a TableCell goes against recommended design principles, it can still be used in certain situations if the drawbacks mentioned below are not significant concerns for your use case:

1. Violation of Separation of Concerns: Mixing UI controls with data representation classes can make the code less modular and harder to maintain.

2. Limited Flexibility: Embedding a Button directly within a TableCell limits the customization options for the button and the cell itself, making it difficult to implement complex interactions or customize styling.

3. Inefficient Memory Usage: Each TableCell instance with a Button consumes additional memory, which can be problematic for large TableViews with many rows.

4. UI Control Focus: Placing a Button within a TableCell may shift the focus from the underlying data to the UI control, potentially affecting the user experience.

Considering these drawbacks, it is generally recommended to follow the recommended design principles and separate the concerns of data representation and UI controls. However, if these drawbacks are not significant for your specific use case and you prefer the simplicity of the original approach, you can proceed with it.

Answer 2

To be able to render the column, TableColumn needs cellValueFactory. But the "action" column does not exist in underlying data model. In this case, I just give some dummy value to cellValueFactory and move on:

public class JustDoIt extends Application {

    private final TableView<Person> table = new TableView<>();
    private final ObservableList<Person> data
            = FXCollections.observableArrayList(
                    new Person("Jacob", "Smith"),
                    new Person("Isabella", "Johnson"),
                    new Person("Ethan", "Williams"),
                    new Person("Emma", "Jones"),
                    new Person("Michael", "Brown")
            );

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

    @Override
    public void start(Stage stage) {
        stage.setWidth(450);
        stage.setHeight(500);

        TableColumn firstNameCol = new TableColumn("First Name");
        firstNameCol.setCellValueFactory(new PropertyValueFactory<>("firstName"));

        TableColumn lastNameCol = new TableColumn("Last Name");
        lastNameCol.setCellValueFactory(new PropertyValueFactory<>("lastName"));

        TableColumn actionCol = new TableColumn("Action");
        actionCol.setCellValueFactory(new PropertyValueFactory<>("DUMMY"));

        Callback<TableColumn<Person, String>, TableCell<Person, String>> cellFactory
                = //
                new Callback<TableColumn<Person, String>, TableCell<Person, String>>() {
            @Override
            public TableCell call(final TableColumn<Person, String> param) {
                final TableCell<Person, String> cell = new TableCell<Person, String>() {

                    final Button btn = new Button("Just Do It");

                    @Override
                    public void updateItem(String item, boolean empty) {
                        super.updateItem(item, empty);
                        if (empty) {
                            setGraphic(null);
                            setText(null);
                        } else {
                            btn.setOnAction(event -> {
                                Person person = getTableView().getItems().get(getIndex());
                                System.out.println(person.getFirstName()
                                        + "   " + person.getLastName());
                            });
                            setGraphic(btn);
                            setText(null);
                        }
                    }
                };
                return cell;
            }
        };

        actionCol.setCellFactory(cellFactory);

        table.setItems(data);
        table.getColumns().addAll(firstNameCol, lastNameCol, actionCol);

        Scene scene = new Scene(new Group());

        ((Group) scene.getRoot()).getChildren().addAll(table);

        stage.setScene(scene);
        stage.show();
    }

    public static class Person {

        private final SimpleStringProperty firstName;
        private final SimpleStringProperty lastName;

        private Person(String fName, String lName) {
            this.firstName = new SimpleStringProperty(fName);
            this.lastName = new SimpleStringProperty(lName);
        }

        public String getFirstName() {
            return firstName.get();
        }

        public void setFirstName(String fName) {
            firstName.set(fName);
        }

        public String getLastName() {
            return lastName.get();
        }

        public void setLastName(String fName) {
            lastName.set(fName);
        }

    }
}