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我正在将一个 JavaFX 应用程序放在一起，并试图通过在我的程序后端的侦听器表中添加一个匿名类来更改标签的文本。虽然监听器将返回它应该获取的数据，但当匿名类更改标签时，JavaFX 将崩溃。

前端：

public class App extends Application {

...

final BackendElement backendElement = new BackendElement();

...

    @Override
    public void start(Stage mainStage) {

         ...

       GridPane stageContents = generateGridPane(mainStage);

         ...

       mainStage.setScene(new Scene(stageContents));
       mainStage.show();
    }


    private GridPane getGridPane(final Stage mainStage) {

          ...

        final Label labelToBeUpdated = new Label("");

          ...

        backendElement.addModelChangedListener(new ModelChangedListener() {
             @Override
             public void modelChanged(ModelChangedEvent ev) {
                 labelToBeUpdated.setText(ev.getSource()); //<- Causes verbose JFX Exception
             }
        });
    }

ModelChangedListener 和 ModelChangedEvent 只是定制的观察者模式的一部分。该结构绝对有效，因为用简单的错误生产线替换

System.out.println(ev.getSource);

将打印出所需的数据。

我认为私有类的标签不能从匿名类中调用。事实证明，App 类中的 final 字段也不能。有没有办法在不丢失观察者模式的情况下解决这个问题？

这是完整的堆栈跟踪：

Exception in thread "Timer-0" java.lang.IllegalStateException: Not on FX application thread; currentThread = Timer-0
at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:237)
at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:397)
at javafx.scene.Parent$1.onProposedChange(Parent.java:245)
at com.sun.javafx.collections.VetoableObservableList.setAll(VetoableObservableList.java:90)
at com.sun.javafx.collections.ObservableListWrapper.setAll(ObservableListWrapper.java:314)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:602)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.handleControlPropertyChanged(LabeledSkinBase.java:209)
at com.sun.javafx.scene.control.skin.SkinBase$3.changed(SkinBase.java:282)
at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:107)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:196)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.StringPropertyBase.fireValueChangedEvent(StringPropertyBase.java:121)
at javafx.beans.property.StringPropertyBase.markInvalid(StringPropertyBase.java:128)
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:161)
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:67)
at javafx.beans.property.StringProperty.setValue(StringProperty.java:84)
at javafx.scene.control.Labeled.setText(Labeled.java:135)
at ui.App$12.modelChanged(App.java:349)
at ui.BackendElement$CustomTimerTask.informAllListeners(BackendElement.java:108)
at ui.BackendElement$CustomTimerTask.access$0(BackendElement.java:105)
at ui.BackendElement$CustomTimerTask$1.run(BackendElement.java:87)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
4

1 回答 1

4

解决方案：使用 Platform.runLater() 包装您希望侦听器执行的任何操作。

        @Override
        public void modelChanged(ModelChangedEvent ev) {

            final ModelChangedEvent event = ev;

            Platform.runLater(new Runnable(){
                @Override
                public void run() {
                    labelToBeChanged.setText((String)event.getSource());
                }
            });
        }
于 2013-06-12T23:47:13.583 回答