Simple javafx eventhandler throws exception - exception

Question

Take the Example 13-3 "Implementing a Cell Factory" from
http://docs.oracle.com/javafx/2/ui_controls/tree-view.htm
and add the lines
box.addEventHandler(EventType.ROOT, new EventHandler<Event>() {
#Override
public void handle(Event event) {
System.out.println("event "+event);
}
});
in the start method then the following exceptions will be thrown when double clicking
an employee node:
java.lang.ClassCastException: javafx.scene.layout.VBox cannot be cast to javafx.scene.control.TreeView
at javafx.scene.control.TreeView$EditEvent.getSource(TreeView.java:988)
at javafx.scene.control.TreeView$EditEvent.getSource(TreeView.java:965)
at com.sun.javafx.event.EventHandlerManager.fixEventSource(EventHandlerManager.java:225)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:216)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Node.fireEvent(Node.java:6863)
at javafx.scene.control.TreeCell.startEdit(TreeCell.java:315)
at test.TreeViewSample$TextFieldTreeCellImpl.startEdit(TreeViewSample.java:100)
at javafx.scene.control.TreeCell.updateEditing(TreeCell.java:435)
at javafx.scene.control.TreeCell.access$500(TreeCell.java:67)
at javafx.scene.control.TreeCell$6.invalidated(TreeCell.java:151)
at javafx.beans.WeakInvalidationListener.invalidated(WeakInvalidationListener.java:80)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:359)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ReadOnlyObjectWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyObjectWrapper.java:195)
at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:161)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:130)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:163)
at javafx.scene.control.TreeView.setEditingItem(TreeView.java:573)
at javafx.scene.control.TreeView.edit(TreeView.java:771)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.simpleSelect(TreeCellBehavior.java:257)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.doSelect(TreeCellBehavior.java:213)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.mouseReleased(TreeCellBehavior.java:132)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3328)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3168)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3123)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1563)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2265)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
at com.sun.glass.ui.View.notifyMouse(View.java:922)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
at java.lang.Thread.run(Unknown Source)
Is this a bug or did I something wrong?
Full example code (you will need to include the files "root.png" and "department.png" in the same directory):
package test;
import java.util.*;
import javafx.application.*;
import javafx.beans.property.*;
import javafx.event.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.image.*;
import javafx.scene.input.*;
import javafx.scene.layout.*;
import javafx.scene.paint.*;
import javafx.stage.*;
import javafx.util.*;
public class TreeViewSample extends Application {
private final Node rootIcon =
new ImageView(new Image(getClass().getResourceAsStream("root.png")));
private final Image depIcon =
new Image(getClass().getResourceAsStream("department.png"));
List<Employee> employees = Arrays.<Employee>asList(
new Employee("Ethan Williams", "Sales Department"),
new Employee("Emma Jones", "Sales Department"),
new Employee("Michael Brown", "Sales Department"),
new Employee("Anna Black", "Sales Department"),
new Employee("Rodger York", "Sales Department"),
new Employee("Susan Collins", "Sales Department"),
new Employee("Mike Graham", "IT Support"),
new Employee("Judy Mayer", "IT Support"),
new Employee("Gregory Smith", "IT Support"),
new Employee("Jacob Smith", "Accounts Department"),
new Employee("Isabella Johnson", "Accounts Department"));
TreeItem<String> rootNode =
new TreeItem<String>("MyCompany Human Resources", rootIcon);
public static void main(String[] args) {
Application.launch(args);
}
#Override
public void start(Stage stage) {
rootNode.setExpanded(true);
for (Employee employee : employees) {
TreeItem<String> empLeaf = new TreeItem<String>(employee.getName(), new ImageView(depIcon));
boolean found = false;
for (TreeItem<String> depNode : rootNode.getChildren()) {
if (depNode.getValue().contentEquals(employee.getDepartment())){
depNode.getChildren().add(empLeaf);
found = true;
break;
}
}
if (!found) {
TreeItem<String> depNode = new TreeItem<String>(
employee.getDepartment(),
new ImageView(depIcon)
);
rootNode.getChildren().add(depNode);
depNode.getChildren().add(empLeaf);
}
}
stage.setTitle("Tree View Sample");
VBox box = new VBox();
final Scene scene = new Scene(box, 400, 300);
scene.setFill(Color.LIGHTGRAY);
TreeView<String> treeView = new TreeView<String>(rootNode);
treeView.setEditable(true);
treeView.setCellFactory(new Callback<TreeView<String>,TreeCell<String>>(){
#Override
public TreeCell<String> call(TreeView<String> p) {
return new TextFieldTreeCellImpl();
}
});
box.getChildren().add(treeView);
stage.setScene(scene);
stage.show();
box.addEventHandler(EventType.ROOT, new EventHandler<Event>() {
#Override
public void handle(Event event) {
System.out.println("event "+event);
}
});
}
private final class TextFieldTreeCellImpl extends TreeCell<String> {
private TextField textField;
public TextFieldTreeCellImpl() {
}
#Override
public void startEdit() {
super.startEdit();
if (textField == null) {
createTextField();
}
setText(null);
setGraphic(textField);
textField.selectAll();
}
#Override
public void cancelEdit() {
super.cancelEdit();
setText((String) getItem());
setGraphic(getTreeItem().getGraphic());
System.out.println(" item canceled "+getItem());
}
#Override
public void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
if (empty) {
setText(null);
setGraphic(null);
} else {
if (isEditing()) {
if (textField != null) {
textField.setText(getString());
}
setText(null);
setGraphic(textField);
} else {
setText(getString());
setGraphic(getTreeItem().getGraphic());
}
}
}
private void createTextField() {
textField = new TextField(getString());
textField.setOnKeyReleased(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent t) {
if (t.getCode() == KeyCode.ENTER) {
commitEdit(textField.getText());
} else if (t.getCode() == KeyCode.ESCAPE) {
cancelEdit();
}
}
});
}
private String getString() {
return getItem() == null ? "" : getItem().toString();
}
}
public static class Employee {
private final SimpleStringProperty name;
private final SimpleStringProperty department;
private Employee(String name, String department) {
this.name = new SimpleStringProperty(name);
this.department = new SimpleStringProperty(department);
}
public String getName() {
return name.get();
}
public void setName(String fName) {
name.set(fName);
}
public String getDepartment() {
return department.get();
}
public void setDepartment(String fName) {
department.set(fName);
}
}
}

Answer 1

Indeed there is a little problem with their code.
You can avoid this exception by removing these lines :
box.addEventHandler(EventType.ROOT, new EventHandler<Event>() {
#Override
public void handle(Event event) {
System.out.println("event "+event);
}
});
This is the source of the problem. The Vbox catches every event thrown (because you told it to do so with EventType.ROOT). And I suspect it to catch an event thrown by the TreeCell or the TreeView when you double click.
It would work better with this because it will only catch input events from the user:
box.addEventHandler(InputEvent.ANY , new EventHandler<InputEvent>()