JavaFX 2 TableView how to update cell when object is changed

Question

I'm creating a TableView to show information regarding a list of custom objects (EntityEvents).

The table view must have 2 columns. First column to show the corresponding EntityEvent's name. The second column would display a button. The button text deppends on a property of the EntityEvent. If the property is ZERO, it would be "Create", otherwise "Edit".

I managed to do it all just fine, except that I can't find a way to update the TableView line when the corresponding EntityEvent object is changed.

Very Important: I can't change the EntityEvent class to use JavaFX properties, since they are not under my control. This class uses PropertyChangeSupport to notify listeners when the monitored property is changed.

Note: I realize that adding new elements to the List would PROBABLY cause the TableView to repaint itself, but that is not what I need. I say PROBABLY because I've read about some bugs that affect this behavior. I tried using this approach to force the repaint, by I couldn't make it work.

Does anyone knows how to do it?

Thanks very much.

Here is a reduced code example that illustrates the scenario:

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

import javafx.application.Application;
import javafx.beans.property.ReadOnlyStringWrapper;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableColumn.CellDataFeatures;
import javafx.scene.control.TableView;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Callback;

public class Main extends Application {

    //=============================================================================================
    public class EntityEvent {
        private String m_Name;
        private PropertyChangeSupport m_NamePCS = new PropertyChangeSupport(this);
        private int m_ActionCounter;
        private PropertyChangeSupport m_ActionCounterPCS = new PropertyChangeSupport(this);

        public EntityEvent(String name, int actionCounter) {
            m_Name = name;
            m_ActionCounter = actionCounter;
        }

        public String getName() {
            return m_Name;
        }

        public void setName(String name) {
            String lastName = m_Name;
            m_Name = name;
            System.out.println("Name changed: " + lastName + " -> " + m_Name);
            m_NamePCS.firePropertyChange("Name", lastName, m_Name);
        }

        public void addNameChangeListener(PropertyChangeListener listener) {
            m_NamePCS.addPropertyChangeListener(listener);
        }   

        public int getActionCounter() {
            return m_ActionCounter;
        }

        public void setActionCounter(int actionCounter) {
            int lastActionCounter = m_ActionCounter;
            m_ActionCounter = actionCounter;
            System.out.println(m_Name + ": ActionCounter changed: " + lastActionCounter + " -> " + m_ActionCounter);
            m_ActionCounterPCS.firePropertyChange("ActionCounter", lastActionCounter, m_ActionCounter);
        }

        public void addActionCounterChangeListener(PropertyChangeListener listener) {
            m_ActionCounterPCS.addPropertyChangeListener(listener);
        }   
    }

    //=============================================================================================
    private class AddPersonCell extends TableCell<EntityEvent, String> {
        Button m_Button = new Button("Undefined");
        StackPane m_Padded = new StackPane();

        AddPersonCell(final TableView<EntityEvent> table) {
            m_Padded.setPadding(new Insets(3));
            m_Padded.getChildren().add(m_Button);

            m_Button.setOnAction(new EventHandler<ActionEvent>() {
                @Override public void handle(ActionEvent actionEvent) {
                    // Do something
                }
            });
        }

        @Override protected void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (!empty) {
                setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
                setGraphic(m_Padded);
                m_Button.setText(item);
            }
        }
    }

    //=============================================================================================
    private ObservableList<EntityEvent> m_EventList;

    //=============================================================================================
    @SuppressWarnings("unchecked")
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Table View test.");

        VBox container = new VBox();

        m_EventList = FXCollections.observableArrayList(
                new EntityEvent("Event 1", -1),
                new EntityEvent("Event 2", 0),
                new EntityEvent("Event 3", 1)
                );
        final TableView<EntityEvent> table = new TableView<EntityEvent>();
        table.setItems(m_EventList);            

        TableColumn<EntityEvent, String> eventsColumn = new TableColumn<>("Events");
        TableColumn<EntityEvent, String> actionCol = new TableColumn<>("Actions");
        actionCol.setSortable(false);

        eventsColumn.setCellValueFactory(new Callback<CellDataFeatures<EntityEvent, String>, ObservableValue<String>>() {
            public ObservableValue<String> call(CellDataFeatures<EntityEvent, String> p) {
                EntityEvent event = p.getValue();
                event.addActionCounterChangeListener(new PropertyChangeListener() {
                    @Override
                    public void propertyChange(PropertyChangeEvent event) {
                        // TODO: I'd like to update the table cell information.
                    }
                });
                return new ReadOnlyStringWrapper(event.getName());
            }
        });

        actionCol.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<EntityEvent, String>, ObservableValue<String>>() {
            @Override
            public ObservableValue<String> call(TableColumn.CellDataFeatures<EntityEvent, String> ev) {
                String text = "NONE";
                if(ev.getValue() != null) {
                    text = (ev.getValue().getActionCounter() != 0) ? "Edit" : "Create";
                }
                return new ReadOnlyStringWrapper(text);
            }
        });

        // create a cell value factory with an add button for each row in the table.
        actionCol.setCellFactory(new Callback<TableColumn<EntityEvent, String>, TableCell<EntityEvent, String>>() {
            @Override
            public TableCell<EntityEvent, String> call(TableColumn<EntityEvent, String> personBooleanTableColumn) {
                return new AddPersonCell(table);
            }
        });

        table.getColumns().setAll(eventsColumn, actionCol);
        table.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY);

        // Add Resources Button
        Button btnInc = new Button("+");
        btnInc.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent ev) {
                System.out.println("+ clicked.");
                EntityEvent entityEvent = table.getSelectionModel().getSelectedItem();
                if (entityEvent == null) {
                    System.out.println("No Event selected.");
                    return;
                }
                entityEvent.setActionCounter(entityEvent.getActionCounter() + 1);
                // TODO: I expected the TableView to be updated since I modified the object.
            }
        });

        // Add Resources Button
        Button btnDec = new Button("-");
        btnDec.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent ev) {
                System.out.println("- clicked.");
                EntityEvent entityEvent = table.getSelectionModel().getSelectedItem();
                if (entityEvent == null) {
                    System.out.println("No Event selected.");
                    return;
                }
                entityEvent.setActionCounter(entityEvent.getActionCounter() - 1);
                // TODO: I expected the TableView to be updated since I modified the object.
            }
        });

        container.getChildren().add(table);
        container.getChildren().add(btnInc);
        container.getChildren().add(btnDec);

        Scene scene = new Scene(container, 300, 600, Color.WHITE);        

        primaryStage.setScene(scene);

        primaryStage.show();
    }

    //=============================================================================================
    public Main() {
    }

    //=============================================================================================
    public static void main(String[] args) {
        launch(Main.class, args);
    }

}

James_D · Accepted Answer · 2014-04-04 18:27:49Z

4

Try the javafx.beans.property.adapter classes, particularly JavaBeanStringProperty and JavaBeanIntegerProperty. I haven't used these, but I think you can do something like

TableColumn<EntityEvent, Integer> actionCol = new TableColumn<>("Actions");
actionCol.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<EntityEvent, Integer> ev) {
    return new JavaBeanIntegerPropertyBuilder().bean(ev.getValue()).name("actionCounter").build();
});

// ...

public class AddPersonCell extends TableCell<EntityEvent, Integer>() {
    final Button button = new Button();

    public AddPersonCell() {
        setPadding(new Insets(3));
        setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
        button.setOnAction(...);
    }

    @Override
    public void updateItem(Integer actionCounter, boolean empty) {
        if (empty) {
            setGraphic(null);
        } else {
            if (actionCounter.intValue()==0) {
                button.setText("Create");
            } else {
                button.setText("Add");
            }
            setGraphic(button);
        }
    }
}

As I said, I haven't used the Java bean property adapter classes, but the idea is that they "translate" property change events to JavaFX change events. I just typed this in here without testing, but it should at least give you something to start with.

UPDATE: After a little experimenting, I don't think this approach will work if your EntityEvent is really set up the way you showed it in your code example. The standard Java beans bound properties pattern (which the JavaFX property adapters rely on) has a single property change listener and an addPropertyChangeListener(...) method. (The listeners can query the event to see which property changed.)

I think if you do

public class EntityEvent {
    private String m_Name;
    private PropertyChangeSupport pcs = new PropertyChangeSupport(this);
    private int m_ActionCounter;

    public EntityEvent(String name, int actionCounter) {
        m_Name = name;
        m_ActionCounter = actionCounter;
    }

    public String getName() {
        return m_Name;
    }

    public void setName(String name) {
        String lastName = m_Name;
        m_Name = name;
        System.out.println("Name changed: " + lastName + " -> " + m_Name);
        pcs.firePropertyChange("name", lastName, m_Name);
    }

    public void addPropertyChangeListener(PropertyChangeListener listener) {
        pcs.addPropertyChangeListener(listener);
    }   

    public void removePropertyChangeListener(PropertyChangeListener listener) {
        pcs.removePropertyChangeListener(listener);
    }

    public int getActionCounter() {
        return m_ActionCounter;
    }

    public void setActionCounter(int actionCounter) {
        int lastActionCounter = m_ActionCounter;
        m_ActionCounter = actionCounter;
        System.out.println(m_Name + ": ActionCounter changed: " + lastActionCounter + " -> " + m_ActionCounter);
        pcs.firePropertyChange("ActionCounter", lastActionCounter, m_ActionCounter);
    }

}

it will work with the adapter classes above. Obviously, if you have existing code calling the addActionChangeListener and addNameChangeListener methods you would want to keep those existing methods and the existing property change listeners, but I see no reason you can't have both.

edited Apr 4, 2014 at 18:27

answered Apr 4, 2014 at 15:04

James_D

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6 Comments

Marcus Over a year ago

Actually the EntityEvent can be changed. However I can't add JavaFX properties to that. It has to be UI domain independent. I'm going to make a few tests. I'll let you know if I get something.

James_D Over a year ago

Since JavaFX is now part of the core JDK, and JavaFX properties don't rely on any native UI resources (i.e. they run in headless mode), you could argue fairly convincingly that introducing JavaFX properties is a UI domain independent change.

Marcus Over a year ago

I agree with you, but this time I can't add the JavaFX properties to the EntityEvent class. I'm doing a few tests and will be back here soon. Thanks very much.

Marcus Over a year ago

I couldn't make it work. The table is not updated at all. Are you sure that would force the table to be repainted?

Marcus Over a year ago

Very strange! My code doesn't work and yours did. Probably some minor mistake in here. That solves my problem perfectly. Thank you very much again.

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