Breaking JavaFX when Tab character is pasted into TextField

Question

The JavaFX Application Thread throws a StringIndexOutOfBoundsException if the user pastes a tab character into a TextField. How can I smartly prevent a user from breaking my application in this way?

Here's a minimal example that demonstrates the behavior.

//Defined in Main.java
public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            AnchorPane root = (AnchorPane) FXMLLoader
                    .load(getClass().getResource("MainView.fxml"));
            primaryStage.setScene(new Scene(root));
            primaryStage.show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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

Defined in MainView.fxml:

<AnchorPane xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
    <children>
        <TextField fx:id="tf" />
    </children>
</AnchorPane>

Procedure:

Copy a tab character (\t) to the clipboard
Type something into the TextField
Highlight the text in the TextField
Paste the contents of the clipboard to replace the highlighted text

The exception occurs whether the user uses the keyboard shortcut (Ctrl+V in Windows) or the context menu. I certainly could add a try-catch block to every TextField, but that would clutter up the code, and how do I know that this exception is only thrown in this one situation?

Note: This is issue does not appear to affect TextArea

Full text of the exception:

Exception in thread "JavaFX Application Thread" java.lang.StringIndexOutOfBoundsException: String index out of range: 1
at java.lang.AbstractStringBuilder.substring(Unknown Source)
at java.lang.StringBuilder.substring(Unknown Source)
at javafx.scene.control.TextField$TextFieldContent.get(Unknown Source)
at javafx.scene.control.TextInputControl.getText(Unknown Source)
at javafx.scene.control.TextInputControl.updateContent(Unknown Source)
at javafx.scene.control.TextInputControl.replaceText(Unknown Source)
at javafx.scene.control.TextInputControl.replaceText(Unknown Source)
at javafx.scene.control.TextInputControl.replaceSelection(Unknown Source)
at javafx.scene.control.TextInputControl.paste(Unknown Source)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.paste(Unknown Source)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callAction(Unknown Source)
at com.sun.javafx.scene.control.behavior.BehaviorBase.callActionForEvent(Unknown Source)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callActionForEvent(Unknown Source)
at com.sun.javafx.scene.control.behavior.BehaviorBase.lambda$new$74(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler$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.EventUtil.fireEventImpl(Unknown Source)
at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
at javafx.event.Event.fireEvent(Unknown Source)
at javafx.scene.Scene$KeyHandler.process(Unknown Source)
at javafx.scene.Scene$KeyHandler.access$1800(Unknown Source)
at javafx.scene.Scene.impl_processKeyEvent(Unknown Source)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Unknown Source)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(Unknown Source)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleKeyEvent$353(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(Unknown Source)
at com.sun.glass.ui.View.handleKeyEvent(Unknown Source)
at com.sun.glass.ui.View.notifyKey(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(Unknown Source)
at java.lang.Thread.run(Unknown Source)

the code you posted is not helping us at all, we need to see the code where you are manipulating the StringBuilder — ΦXocę 웃 Пepeúpa ツ, Mar 15 '16 at 11:04
@Xoce웃Пepeúpa I don't manipulate the `StringBuilder`; it's internal to the `TextField` implementation. The code I posted is a *full* minimal example that can reproduce the results. — Austin, Mar 15 '16 at 11:06
you are right. I just tried it at my own application. I've got the same problem. — griFlo, Mar 15 '16 at 11:24

James_D · Accepted Answer · 2016-03-15T19:43:38.413

Well that's ugly. You should report this as a bug.

You can workaround this with a TextFormatter which filters out tab (and newline) characters. You might want to replace the tab character with, e.g. four spaces.

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.control.TextFormatter;
import javafx.scene.control.TextFormatter.Change;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class TextFieldBug extends Application {

    @Override
    public void start(Stage primaryStage) {
        TextField tf = new TextField();
        tf.setTextFormatter(new TextFormatter<String>((Change c) -> {
            String text = c.getText();
            int oldAnchor = c.getAnchor();
            int oldCaretPos = c.getCaretPosition() ;
            int initialLength = text.length();
            text = text.replaceAll("\t", "    ");
            text = text.replaceAll("\n", "");
            c.setText(text);
            c.setAnchor(oldAnchor + text.length() - initialLength);
            c.setCaretPosition(oldCaretPos + text.length() - initialLength);
            return c ;
        }));
        primaryStage.setScene(new Scene(new StackPane(tf), 350, 120));
        primaryStage.show();
    }

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

score 0 · Answer 2 · edited May 23 '17 at 11:52

0

Seems to be a bug. As a workaround, you could handle the error in the DefaultUncaughtEcxeptionHanlder such that the application doesn't crash (see e..g. General Exception handling in JavaFX 8)

edited May 23 '17 at 11:52

Community

1
1

answered Mar 15 '16 at 20:30

Raphael Roth

26,751
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score 0 · Answer 3 · answered Oct 14 '18 at 18:01

I experienced the same problem with the javafx.scene.control.TextField, so I reported it as a bug: https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8212102 / https://bugs.openjdk.java.net/browse/JDK-8212102. The Oracle people say that this is a regression in JDK 8u40. As long as it's not fixed the workaround James_D suggested works like a charm.

Breaking JavaFX when Tab character is pasted into TextField

3 Answers3