Простой JavaFX EventHandler бросает исключение

Question

Возьмите пример 13-3 «Реализация фабрики ячеек» из http://docs.oracle.com/javafx/2/ui_controls/tree-view.htm и добавьте строки

box.addEventHandler(EventType.ROOT, new EventHandler<Event>() { 
@Override 
    public void handle(Event event) { 
     System.out.println("event "+event); 
    } 
}); 

в методе запуска, то следующие исключения будут отброшены при двойном нажатии узел сотрудника:

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) 

Это ошибка, или я что-то не так?

Полный пример кода (вам нужно будет включить файлы «root.png» и «department.png» в том же каталоге):

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

Действительно есть небольшая проблема с их кодом. Вы можете избежать этого исключения, удалив эти строки:

box.addEventHandler(EventType.ROOT, new EventHandler<Event>() { 
     @Override 
     public void handle(Event event) { 
       System.out.println("event "+event); 
     } 
    }); 

Это источник проблемы. Vbox ловит каждое событие (потому что вы сказали ему сделать это с помощью EventType.ROOT). И я подозреваю, что он поймал событие, выброшенное TreeCell или TreeView при двойном щелчке.

Было бы лучше работать с этим, потому что это будет только поймать событие ввода от пользователя:

box.addEventHandler(InputEvent.ANY , new EventHandler<InputEvent>()