ArrayIndexOutOfBoundsException - possible bug in JTextField?

[berkeleybross]

Hey all,

I keep getting a rather weird glitch:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 10
        at sun.font.FontDesignMetrics.charsWidth(FontDesignMetrics.java:492)
        at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:381)
        at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:302)
        at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:286)
        at javax.swing.text.PlainView.viewToModel(PlainView.java:403)
        at javax.swing.text.FieldView.viewToModel(FieldView.java:263)
        at javax.swing.plaf.basic.BasicTextUI$RootView.viewToModel(BasicTextUI.java:1540)
        at javax.swing.plaf.basic.BasicTextUI.viewToModel(BasicTextUI.java:1089)
        at javax.swing.text.DefaultCaret.positionCaret(DefaultCaret.java:292)
        at javax.swing.text.DefaultCaret.adjustCaret(DefaultCaret.java:497)
        at javax.swing.text.DefaultCaret.adjustCaretAndFocus(DefaultCaret.java:485)
        at javax.swing.text.DefaultCaret.mousePressed(DefaultCaret.java:475)
        at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:263)
        at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
        at java.awt.Component.processMouseEvent(Component.java:6260)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3255)
        at java.awt.Component.processEvent(Component.java:6028)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4235)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

This occurs seemingly at random, when the caret is after the last character in a JTextField. (In this instance the JTextField had 10characters in it - so the array index out of bounds makes sense)
None of the methods throwing an error in the stack trace above are mine, so i was wondering if anybody can confirm it is a bug in Java?

I realise that my first thought shouldnt be that its a bug with java and it is more likely a bug in my code, but I tested it on a blank form with just a JTextField in, and it still throws the error (About once in a hundred times).

I tried googling it, but for some reason ArrayIndexOutOfBounds is a fairly commonly asked question >.<

my java version is:
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing)

- running on windows 7 32-bit

Thanks for your time,
berkeleybross

[Tolls]

Are you using a non-standard font?

[berkeleybross]

No, Im using the default font.

I've finally found a bug report here

The last post was in september last year, and it *says* the bug was fixed and will be released in a future SDK... but ive got a later version and it still occurs.

I dont want to just catch an arrayindexoutofbounds exception, incase i make a mistake later on and dont notice it...

berkeleybross

[JosAH]

Hey all,

I keep getting a rather weird glitch:
[code]
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 10

Are you sure you don't have an array of some sort with less than ten elements and pass that array on to some built-in class method?

kind regards,

Jos

[berkeleybross]

Hi Jos,
Fairly sure :S
Even if i did, wouldnt it show up somewhere in the stack trace?

this code throws the error as well:

public class Main {
    public static void main (String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame mainFrame = new JFrame ("demo");
                mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                mainFrame.getContentPane().add(new JTextField ());

                mainFrame.pack();
                mainFrame.setVisible(true);
            }
        });
    }
}

Actually trying to reproduce the problem is surprisingly difficult, but accidentally doing it is stupidly easy.

As the bug i posted above says:
To reproduce:
-Run the program below
-start typing text in the text field
-while typing, keep drag-selecting text from the right to the left (selected text gets replaced by what you type)
-should get error

berkeleybross

ps woop 100th post here :)

[Tolls]

So you're adding text at the same time as drag/select that text?

Might I suggest not doing that...;)

[JosAH]

To reproduce:
-Run the program below
-start typing text in the text field
-while typing, keep drag-selecting text from the right to the left (selected text gets replaced by what you type)
-should get error

I ran your code but I couldn't manage to make it crash ... the code is so simple and looks ok to me ...

kind regards,

Jos

[berkeleybross]

haha yeah its a bit of a weird description.

Its slightly more complicated then i've suggested, as the program is selecting the text.

Basically what im trying to make is a DatePicker. When the user presses a seperator key, such as "-" or "/" or tab, the program selects the next part of the date automatically, so when the user types it replaces the whole month instead of making the user delete the whole month.

It all works, but it throws the error when the user is typing the last part of the date.

berkeleybross

[berkeleybross]

Jos -

Actually trying to reproduce the problem is surprisingly difficult, but accidentally doing it is stupidly easy.

:P

It happens about once in a hundred attempts for me, but i assure you it does happen.
I just tried it now, to prove my sanity, and it took me about two minutes of constant typing whilst highlighted before it occured.

Maybe the fact I'm automatically highlighting the text means its slightly more likely to happen than otherwise, but in any case it shouldnt happen at all.

berkeleybross

[JosAH]

So you're adding text at the same time as drag/select that text?

Might I suggest not doing that...;)

It doesn't matter because processing keys and mouse movements and updating the text field all happens in one thread, the EDT; they're all handled one by one (very quickly, giving the impression that things happen at the same time). The code posted doesn't use other threads so all is sound.

kind regards,

Jos

[JosAH]

Jos - :P

It happens about once in a hundred attempts for me, but i assure you it does happen.
I just tried it now, to prove my sanity, and it took me about two minutes of constant typing whilst highlighted before it occured.

Maybe the fact I'm automatically highlighting the text means its slightly more likely to happen than otherwise, but in any case it shouldnt happen at all.

berkeleybross

Sorry, I am not able to reproduce the said bug: I typed like a madman for a couple of minutes while trying to continuously select parts of the text. All went fine and my wife is frowning at me now ... ;-)

kind regards,

Jos

[berkeleybross]

Heh, oh well thanks for trying.

I guess I'll just catch the exception and ignore it for now. If it causes signifcant problems I will come back and ask for more help :)

Thanks for helping,
berkeleybross