Java run time error that won't go away

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Java run time error that won't go away

Postby robusto » Tue Jun 03, 2014 11:44 am

I must say I am pretty disappointed with lejos for the EV3 - it's hopelessly slow to boot up and pretty buggy.
These two factors are combining for me with a Java runtime error ("com.sun.jna.LastErrorException was 19") that appears on the display after Start Menu and won't go away. Pressing the brick "escape" key subsequently from any level of the menu causes the brick to shutdown.
I've tried removing and replacing the batteries and the sd card, and rebooted but the same errors occurs.
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Re: Java run time error that won't go away

Postby gloomyandy » Tue Jun 03, 2014 12:00 pm

Never seen that error, or had any reports of it on the forum or from other developers and users. It would help if you gave the details of what version of leJOS you are using and how you have created your sdcard. Did you make any changes to the standard configuration? Are you saying that a single pres of the escape key shuts down the EV3? again I have never seen or had the behavior reported, you will normally be prompted to confirm the shutdown action.

Please provide a screen dump (or photo) of your EV3 screen showing the exception message you are getting. When and where does it appear? Does the menu start normally? Where on the screen is the exception displayed (or are you seeing this via some sort of terminal connection). Yes the EV3 is slow to start, but once running it has been very stable for me. what sort of boot times are you seeing. What other bugs are you seeing? If we don't see them or have them reported we are not able to address them.
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Re: Java run time error that won't go away

Postby robusto » Tue Jun 03, 2014 12:37 pm

Thanks Andy.
I'll provide a screen dump in a little while but here's some more detail for the time being.

I installed lejos on the ev3 in the recommended manner. I have not made changes to the standard configuration and I've successfully installed and run programs on the brick.

Problems started when one of my applications crashed with a run time error. I've diagnosed the bug in the code but the really annoying thing is that a Java run time error seems to freeze the brick. I can't find anyway to start up again when this happens apart from removing and replacing the batteries. Anyway, that's another problem I hope you can help me with.

The main issue now though is a run time error appearing on the brick display that won't disappear. The brick goes through the boot process normally but then the error appears covering or half covering the menu. Strangely, when I can see what I am doing (underneath the error text) , I can run an existing program no problems.So I think the error must be coming from the boot code . Maybe it isn't an error, just a trace that's wrongly appearing?

The first line is:
com.sun.jna.LastErrorException was 19
then
lejos.internal.io.NativeHCI$LIbBlue.hci..

then a couple of more lines including
lejos.hardware.Bluetooth.getLocal <<something>>

it's very difficult to read it all.

Yes, if I press the escape key once and I don't get the usual choice of cancelling or exiting. The X and the tick do appear but then fade immediately and the brick just starts shutting down.


Guess I am looking recreating the SD card, right?
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Re: Java run time error that won't go away

Postby gloomyandy » Tue Jun 03, 2014 1:07 pm

Sounds like all of this removing the batteries has corrupted the file system in some way and that is resulting in the error you are seeing. So yes I would recreate the sdcard. Given the problem you are seeing I would be tempted to reformat the card and start over. I remember you had problems with the sd card originally, but I assume you fixed them, did you ever post to say what the problem was and how you resolved it?

You should not really ever need to remove the batteries like this to fix a problem, so please post the details (in a new thread) of what it was that was getting you into that state. I assume that the standard leJOS reset of the program did not work (ENTER+DOWN keys pressed at the same time)?
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Re: Java run time error that won't go away

Postby robusto » Tue Jun 03, 2014 1:30 pm

My previous problem was (I am ashamed to say) solved by ejecting the SD card properly.
I did not know about the Enter + DOWN key combination so I can't say if it worked or not.
So it looks like all my own doing.

Just one thing though - I think this current error might have appeared the first time after the brick shut down when the batteries died. I put in new batteries and the problem started. I asssume the power management hasn't been causing any problems?

Thanks again.
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Re: Java run time error that won't go away

Postby gloomyandy » Tue Jun 03, 2014 2:15 pm

It is always hard to say what causes problems like this. I have had my EV3 shutdown many, many times due to the batteries running out and have never seen any problems from it, but I may just have been lucky!
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Re: Java run time error that won't go away

Postby lawrie » Tue Jun 03, 2014 5:31 pm

You get that error when the Bluetooth device is not available, which is probably due to some corruption of the Linux system. The latest menu traps it and you just do not get Bluetooth access.
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