TreeTableColumn.visible : A bound value cannot be set

Question

I make a simple JavaFX application. In this application there is a treetable with 2 columns and a check box. If check box is selected column 2 will be visible, otherwise not visible. To do this I bound tree table column visible property to checkbox selected property. When I click the check box column state change but at the same time gives.

Caused by: java.lang.RuntimeException: TreeTableColumn.visible : A bound value cannot be set.

If I use bidirectional binding I don't get this error. But I don't need bidirectional binding. Is it a bug or I don't use bind correctly? Please use below code to reproduce this error. I use jdk1.8.0_111.

JavaFXApplication.java

package test;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class JavaFXApplication extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

        Scene scene = new Scene(root);

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

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}

FXMLDocumentController.java

package test;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.CheckBox;
import javafx.scene.control.Label;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableView;

public class FXMLDocumentController implements Initializable {

    @FXML
    private TreeTableView<?> table;
    @FXML
    private CheckBox box;
    @FXML
    private TreeTableColumn<?, ?> c2;

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
        c2.visibleProperty().bind(box.selectedProperty());
    }    

}

FXMLDocument.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.CheckBox?>
<?import javafx.scene.control.TreeTableColumn?>
<?import javafx.scene.control.TreeTableView?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="390.0" prefWidth="452.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.65" fx:controller="javafxapplication2.FXMLDocumentController">
    <children>
      <TreeTableView fx:id="table" layoutX="2.0" prefHeight="390.0" prefWidth="149.0">
        <columns>
          <TreeTableColumn prefWidth="75.0" text="C1" />
          <TreeTableColumn fx:id="c2" prefWidth="75.0" text="C2" visible="false" />
        </columns>
      </TreeTableView>
      <CheckBox fx:id="box" layoutX="234.0" layoutY="77.0" mnemonicParsing="false" text="CheckBox" />
    </children>
</AnchorPane>

Answer 1

I think this actually is not a bug. It's definitely mysterious and unexpected behavior though. Part of the problem is that the binding conflict is coming from TableHeaderRow, which is created by the skin at display time.

The TableHeaderRow is responsible for rendering all the column headers, and it includes this built-in button for a menu that, by default, is a radio selection list of columns to show/hide:

As a result, the TableHeaderRow creates a bidirectional binding between these menu entries' selection state and each column's visible property.

It actually is possible to undo this binding but I found it annoying since the TableHeaderRow is null until the TableView is displayed. But, adapting this solution to access the TableHeaderRow, we can do something like:

      TableHeaderRow headerRow = ((TableViewSkinBase) tableView.getSkin()).getTableHeaderRow();
      try {

        // get columnPopupMenu field
        Field privateContextMenuField = TableHeaderRow.class.getDeclaredField("columnPopupMenu");

        // make field public
        privateContextMenuField.setAccessible(true);

        // get context menu
        ContextMenu contextMenu = (ContextMenu) privateContextMenuField.get(headerRow);

        for (MenuItem menuItem : contextMenu.getItems()) {
          // Assuming these will be CheckMenuItems in the default implementation
          BooleanProperty selectedProperty = ((CheckMenuItem) menuItem).selectedProperty();

          // In theory these menu items are in parallel with the columns, but I just brute forced it to test
          for (TableColumn<?, ?> tableColumn : tableView.getColumns()) {
            // Unlink the column's visibility with the menu item
            tableColumn.visibleProperty().unbindBidirectional(selectedProperty);
          }
        }

      } catch (Exception ex) {
        ex.printStackTrace();
      }

      // Not strictly necessary but we don't want to be misleading :-p
      tableView.setTableMenuButtonVisible(false);

But here's the kicker: you have to do this every time a column's visibility changes, because the TableHeaderRow has a listener that rebuilds the menu, and re-links the properties, every time a column is shown.

You could, of course, find a way to disable that listener.. but clearly this is already ridiculous and probably unnecessary.

Anyway, as you noted:

If I use bidirectional binding I don't get this error. But I don't need bidirectional binding.

I think the second statement isn't technically true: your use case doesn't require bidirectional binding, but it is actually appropriate here since there are other properties already linked with a column's visibility.

So, I would use bidirectional binding.