BlackBerry - IllegalStateException ArticInterface::DocPosToCaret

A few days ago, I found another rare BlackBerry bug. I was playing with some list elements and everything was working fine until I ran the code on a BlackBerry Curve 8300.

I was suddenly presented with this popup.

I have never seen this error so I Googled for it. Unfortunately, there was no reasonable explanation. So I decided to investigate it. First thing I did was to take a peek at the event log. I did it by pressing ALT+L+G+L+G and I got this.

Taking a look at the exception trace showed this.

I needed to see the full log for details, so I used:

javaloader -u eventlog

To dump the event log (for this to work, you need to check the USB Cable Connected under the Simulate menu item of the emulator). My javaloader file is located at c:\eclipse_g_341_jde7\plugins\ net.rim.eide.componentpack4.5.0_4.5.0.14\components\bin\JavaLoader.exe.

The log looked like this:

guid:0x9C3CD62E3320B498 time: Mon Nov 23 15:05:00 2009  
severity:1 type:3 app:Java Exception data:
        IllegalStateException
        ArticInterface::DocPosToCaret: error 3; formatted text length = 40;
        net_rim_cldc-11
         TextArea
         getTextBounds
         0x7B8E
        net_rim_cldc-9
         LabelField
         layout
         0x9D99
        net_rim_cldc-8
         Manager
         layoutChild
         0x1B98
        net_rim_cldc-11
         VerticalFieldManager
         sublayout
         0xC6F0
        net_rim_cldc-8
         Manager
         layout
         0x1A95
        net_rim_cldc-8
         Manager
         layoutChild
         0x1B98
        net_rim_cldc-11
         VerticalFieldManager
         sublayout
         0xC6F0
        net_rim_cldc-8
         Manager
         layout
         0x1A95
        net_rim_cldc-8
         Manager
         layoutChild
         0x1B98
        net_rim_cldc-11
         VerticalFieldManager
         sublayout
         0xC6F0
        net_rim_cldc-8
         Manager
         layout
         0x1A95
        net_rim_cldc-8
         Manager
         layoutChild
         0x1B98
        net_rim_cldc-11
         VerticalFieldManager
         sublayout
         0xC6F0
        net_rim_cldc-8
         Manager
         layout
         0x1A95
        net_rim_cldc-8
         Manager
         layoutChild
         0x1B98
        net_rim_cldc-8
         Screen
         layoutDelegate
         0x5375
        net_rim_cldc-2
         MIDPScreen
         sublayout
         0x9781
        net_rim_cldc-8
         Manager
         layout
         0x1A95
        net_rim_cldc-8
         Screen
         doLayout
         0x4B51
        net_rim_cldc-8
         UiEngineImpl
         pushScreen
         0xA538
        net_rim_cldc-8
         UiApplication
         pushScreen
         0x8A4B
        net_rim_cldc-2
         Display
         switchDisplayables
         0x3A60
        net_rim_cldc-2
         Display$SwitchDisplayablesRunnable
         run
         0x3FF5
        net_rim_cldc-5
         Application
         dispatchInvokeLater
         0xAAC
        net_rim_cldc-3
         MIDletMain
         dispatchInvokeLater
         0x4F78
        net_rim_cldc-5
         Application
         processNextMessage
         0x123D
        net_rim_cldc-5
         Application
         enterEventDispatcher
         0xA51
        net_rim_cldc-3
         MIDletMain
         main
         0x51FA
guid:0x97C9F5F641D25E5F time: Mon Nov 23 15:05:00 2009  
severity:0 type:2 app:System data:JVM Error 104
guid:0x97C9F5F641D25E5F time: Mon Nov 23 15:05:00 2009 
severity:0 type:2 app:System data:Uncaught: IllegalStateException

The event log shows a very interesting thing. It seems the J2ME list is rendered as a VerticalLayout that contains Labels.

We start by looking for TextArea. We cannot find it in the SDK so we look for the LabelField class. We find the LabelField in C:\eclipse_g_341_jde7\plugins\net.rim.eide.componentpack4.5.0_4.5.0.14\components\lib\net_rim_api\net\rim\device\api\ui\component\LabelField.class.

A quick look in the documentation of LabelField shows us the setText method can truly throw an IllegalStateException.

public void setText(Object text)

    Sets this field's label text.

    Parameters:
        text - Label text which may be a string, string buffer, character array,
        or byte array (may be null for an empty label).
    Throws:
        IllegalArgumentException - if text parameter is an unsupported type.

Source: BlackBerry JDE 4.5.0 API Reference: Class LabelField

Looking for the getTextBounds method gives us a few results, like C:\eclipse_g_341_jde7\plugins\net.rim.eide.componentpack4.5.0_4.5.0.14\components\lib\net_rim_api\net\rim\device\internal\ui\Formatter.class c:\eclipse_g_341_jde7\plugins\net.rim.eide.componentpack4.5.0_4.5.0.14\components\lib\net_rim_api\net\rim\device\api\ui\component\TextField.class

The method signature looks like:

getTextBounds(IILnet/rim/device/api/ui/XYRect;Lnet/rim/device/internal/ui/ArticInterface$Line;II)

Since the TextArea is not available and the ArticInterface is also missing, we must move our search somewhere else.

What we can notice is the exception thrown has something to do with the caret - DocPosToCaret.

After a little bit of testing, I was able to reproduce the bug. It seems the bug appears when the list item contains a ‘\n’ char right in the beginning of the text and the text following will be long enough to need to be split on different lines.

Also, setting many ‘\n’ chars in the beginning will make the exception pop up for a smaller following text length. Unfortunately, without the code, we cannot say exactly how the algorithm in getTextBounds() works, but still, we now have a good picture of why this happens and how it can be avoided (for example, by removing the ‘\n’ chars from the beginning of the text, or by adding a space “ “ char in front of the text).

Some tech details:

1. This behavior only seems to exist in net.rim.eide.componentpack4.5.0_4.5.0.14 and not other emulators.
2. The bug appears on the BlackBerry Curve 8300 phone.
3. You can download the code to reproduce the bug here ws_DocPosToCaretException.zip (599.40 KB)
4. The emulator specification looks like this:

I hope you have enjoyed this rare to find bug, and if you want to see another one, a really funny one, then please also check this one here BlackBerry - This is sexy, isn’t it?.