在javafx TextArea中删除所选文本时出现异常

Question

我想，这是javafx问题，但并不完全确定。请帮帮我！ 这段代码：

package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
    @Override
    public void start(Stage primaryStage) throws Exception{
         Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
         primaryStage.setTitle("Hello World");
         primaryStage.setScene(new Scene(root, 300, 275));
         primaryStage.show();
    }
    public static void main(String[] args) {
        launch(args);
    }
}

FXML文件：

    <?xml version="1.0" encoding="UTF-8"?>
    <?import javafx.scene.control.TextArea?>
    <?import javafx.scene.layout.ColumnConstraints?>
    <?import javafx.scene.layout.GridPane?>
    <?import javafx.scene.layout.RowConstraints?>
    <GridPane alignment="center" hgap="10" vgap="10" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8" fx:controller="sample.Controller">
   <columnConstraints>
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints />
   </rowConstraints>
   <children>
      <TextArea fx:id="text" prefHeight="900.0" prefWidth="900.0" />
   </children>
</GridPane>

控制器类：

package sample;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.TextArea;
import javafx.scene.input.Clipboard;
import javafx.stage.WindowEvent;
import java.net.URL;
import java.util.ResourceBundle;
public class Controller implements Initializable, EventHandler<WindowEvent> {
private final Clipboard clipboard = Clipboard.getSystemClipboard();
@FXML
private TextArea text;
@Override
public void initialize(URL location, ResourceBundle resources) {
    text.setWrapText(true);
    enableCutAction(false);
    enableCopyAction(false);
    enablePasteAction(clipboard.hasString());
    text.setOnMouseMoved(event -> enablePasteAction(clipboard.hasString()));
    text.selectedTextProperty().addListener(listener -> {
        boolean isSelection = text.getSelectedText().length() != 0;
        enableCutAction(isSelection);
        enableCopyAction(isSelection);
    });
    //sample text
    text.setText("In December 2008, gedit binaries were made available for [[Mac OS X]] and [[Microsoft Windows]].<ref>{{cite web|url=http://blogs.gnome.org/pbor/2008/12/25/late-christmas-gift-for-windows-users/ |title=Club Silencio » Late Christmas gift for Windows users |publisher=Blogs.gnome.org |date=2008-12-25 |accessdate=2009-03-13}}</ref>\n" +
            "\n" +
            "==See also==\n" +
            "{{Portal|Free software}}\n" +
            "*[[List of text editors]]\n" +
            "*[[Comparison of text editors]]\n" +
            "\n" +
            "==References==\n" +
            "{{Reflist|30em}}\n" +
            "\n" +
            "==External links==\n" +
            "{{Spoken Wikipedia|Gedit.ogg|2011-07-31}}\n" +
            "{{Commons category}}\n" +
            "* {{Official website|https://wiki.gnome.org/Apps/Gedit}}\n" +
            "* [http://ftp.gnome.org/pub/GNOME/binaries/win32/gedit/ Gedit for Windows]\n" +
            "\n" +
            "{{GNOME}}\n");
}
private void enableCutAction(boolean state) {
    //code
}
private void enableCopyAction(boolean state) {
    //code
}
private void enablePasteAction(boolean state) {
    //code
}
@Override
public void handle(WindowEvent event) {
    Platform.exit();
    event.consume(); // stop event handling
}
}

当我选择文本（例如从“==外部链接==”到“{{GNOME}}”之前的新行）然后在键盘上按“删除”时，我得到一个例外：

Exception in thread "JavaFX Application Thread" java.lang.StringIndexOutOfBoundsException: String index out of range: 636
at java.lang.String.substring(String.java:1951)
at javafx.scene.control.TextInputControl$2.computeValue(TextInputControl.java:164)
at javafx.beans.binding.StringBinding.get(StringBinding.java:152)
at javafx.beans.binding.StringBinding.get(StringBinding.java:61)
at javafx.beans.binding.StringExpression.getValue(StringExpression.java:51)
at javafx.beans.binding.StringExpression.getValue(StringExpression.java:47)
at javafx.beans.property.StringPropertyBase.get(StringPropertyBase.java:130)
at javafx.scene.control.TextInputControl.getSelectedText(TextInputControl.java:382)
at sample.Controller.lambda$initialize$1(Controller.java:30)
at sample.Controller$$Lambda$73/1546743707.invalidated(Unknown Source)
at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyStringWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyStringWrapper.java:178)
at javafx.beans.property.ReadOnlyStringWrapper.fireValueChangedEvent(ReadOnlyStringWrapper.java:144)
at javafx.beans.property.StringPropertyBase.markInvalid(StringPropertyBase.java:110)
at javafx.beans.property.StringPropertyBase.access$000(StringPropertyBase.java:49)
at javafx.beans.property.StringPropertyBase$Listener.invalidated(StringPropertyBase.java:230)
at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.binding.StringBinding.invalidate(StringBinding.java:171)
at com.sun.javafx.binding.BindingHelperObserver.invalidated(BindingHelperObserver.java:51)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:349)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.scene.control.TextInputControl$TextProperty.fireValueChangedEvent(TextInputControl.java:1386)
at javafx.scene.control.TextInputControl$TextProperty.markInvalid(TextInputControl.java:1390)
at javafx.scene.control.TextInputControl$TextProperty.controlContentHasChanged(TextInputControl.java:1329)
at javafx.scene.control.TextInputControl$TextProperty.access$1600(TextInputControl.java:1297)
at javafx.scene.control.TextInputControl.lambda$new$165(TextInputControl.java:139)
at javafx.scene.control.TextInputControl$$Lambda$70/464632579.invalidated(Unknown Source)
at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.scene.control.TextArea$TextAreaContent.delete(TextArea.java:290)
at javafx.scene.control.TextInputControl.replaceText(TextInputControl.java:1197)
at javafx.scene.control.TextInputControl.updateContent(TextInputControl.java:556)
at javafx.scene.control.TextInputControl.replaceText(TextInputControl.java:548)
at javafx.scene.control.TextInputControl.replaceText(TextInputControl.java:510)
at javafx.scene.control.TextInputControl.replaceSelection(TextInputControl.java:1081)
at javafx.scene.control.TextInputControl.deleteNextChar(TextInputControl.java:917)
at com.sun.javafx.scene.control.skin.TextAreaSkin.deleteChar(TextAreaSkin.java:1337)
at com.sun.javafx.scene.control.behavior.TextAreaBehavior.deleteChar(TextAreaBehavior.java:270)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.deleteNextChar(TextInputControlBehavior.java:315)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callAction(TextInputControlBehavior.java:144)
at com.sun.javafx.scene.control.behavior.TextAreaBehavior.callAction(TextAreaBehavior.java:255)
at com.sun.javafx.scene.control.behavior.BehaviorBase.callActionForEvent(BehaviorBase.java:218)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callActionForEvent(TextInputControlBehavior.java:127)
at com.sun.javafx.scene.control.behavior.BehaviorBase.lambda$new$75(BehaviorBase.java:135)
at com.sun.javafx.scene.control.behavior.BehaviorBase$$Lambda$94/777167913.handle(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$KeyHandler.process(Scene.java:3965)
at javafx.scene.Scene$KeyHandler.access$1800(Scene.java:3911)
at javafx.scene.Scene.impl_processKeyEvent(Scene.java:2040)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:2502)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:197)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:147)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleKeyEvent$349(GlassViewEventHandler.java:228)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$187/327898217.get(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:404)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:227)
at com.sun.glass.ui.View.handleKeyEvent(View.java:546)
at com.sun.glass.ui.View.notifyKey(View.java:956)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
at com.sun.glass.ui.win.WinApplication$$Lambda$39/1651775625.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)

这个片段有什么问题？

Answer 1

这看起来像一个错误：你应该在http://bugreport.java.com/

提交

要获得解决方法，请尝试替换

boolean isSelection = text.getSelectedText().length() != 0;

与

boolean isSelection = text.getSelection().getLength() != 0;

Answer 2

更好的答案是：

boolean isSelection = !text.getSelectText().isEmpty();