JavaFX - ComboBox.setEditable() Index out of Bounds Exception

Question

Я хочу иметь поле со списком, когда выбран конкретный элемент, поле со списком становится редактируемым. К сожалению, мой код для этого продолжает бросать исключение:

package application; 

import javafx.application.Application; 
import javafx.stage.Stage; 
import javafx.scene.Scene; 
import javafx.scene.control.ComboBox; 
import javafx.scene.layout.VBox; 


public class Main extends Application 
{  
    ComboBox<String> comboBox; 

    @Override 
    public void start(Stage primaryStage) 
    { 
    comboBox = new ComboBox<String>(); 
    comboBox.getItems().add("Editable Item"); 
    comboBox.setOnAction(e -> comboBox.setEditable(true)); 

    VBox vBox = new VBox(); 
    vBox.getChildren().add(comboBox); 

    Scene scene = new Scene(vBox, 128, 128); 

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

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

Вот трассировки стека:

Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException 
    at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.subList(Unknown Source) 
    at javafx.collections.ListChangeListener$Change.getAddedSubList(Unknown Source) 
    at com.sun.javafx.scene.control.behavior.ListViewBehavior.lambda$new$178(Unknown Source) 
    at com.sun.javafx.scene.control.behavior.ListViewBehavior$$Lambda$128/1234852073.onChanged(Unknown Source) 
    at javafx.collections.WeakListChangeListener.onChanged(Unknown Source) 
    at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(Unknown Source) 
    at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(Unknown Source) 
    at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.callObservers(Unknown Source) 
    at javafx.scene.control.MultipleSelectionModelBase.clearAndSelect(Unknown Source) 
    at javafx.scene.control.ListView$ListViewBitSetSelectionModel.clearAndSelect(Unknown Source) 
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.simpleSelect(Unknown Source) 
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.doSelect(Unknown Source) 
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(Unknown Source) 
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(Unknown Source) 
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(Unknown Source) 
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(Unknown Source) 
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) 
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) 
    at com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source) 
    at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source) 
    at javafx.event.Event.fireEvent(Unknown Source) 
    at javafx.scene.Scene$MouseHandler.process(Unknown Source) 
    at javafx.scene.Scene$MouseHandler.access$1500(Unknown Source) 
    at javafx.scene.Scene.impl_processMouseEvent(Unknown Source) 
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Unknown Source) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$350(Unknown Source) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$183/1274446857.get(Unknown Source) 
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source) 
    at com.sun.glass.ui.View.handleMouseEvent(Unknown Source) 
    at com.sun.glass.ui.View.notifyMouse(Unknown Source) 
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) 
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source) 
    at com.sun.glass.ui.win.WinApplication$$Lambda$36/1232367853.run(Unknown Source) 
    at java.lang.Thread.run(Unknown Source) 

Кто-нибудь знает, почему это происходит? Можно ли сделать поле со списком редактируемым, когда выбран конкретный элемент?

Answer 1

Ваш NPE брошено этой линией

if(item.equals(editableItem)) 

где item является нулевым. Чтобы сохранить такие уравнения NPE безопасны вы скорее должны сделать

if("editable".equals(item)) 

Это никогда бы не thorw NPE, даже если item будет нулевым.