Topic: Java ME/Mobile

Heya,

Has any of you ever done anything with Java Mobile Edition?

I'm trying to get to grips with it, and either my google foo is lacking these days,
or I'm asking all the wrong questions...

So do we have a pro around here, that I can talk to on any instant messenger, or skype, or the phone,
or something ?

Thanks,
so long,

->Tyberius Prime

I did, a while ago, for Nokia phones - a while ago as in years ago, but I may help.

Good .

Well... where do I start?

I'm worknig with images and the camera... let's see

• how can I capture images that are larger than the memory I have ( for example a 640x480 images, weighting just below 1 MB)... is there any way to take a snapshot, but than handle the image in
  
  'chunks'?
• how can I get the mobile to report exceptions
• is there any way to hook onto the debugging information in the mobile if you're not using windows?
• why is videoControl.getSnapshot 'silently' failing
• how Do I profile on the mobile, or on the emulator for that matter... this thing is dog slow right now .

that's it for a start

thanks for your time,
so long,

->Tyberius Prime

Okay, I haven't adressed the specific issues in two years at least, but while staying general to avoid
too specific and false advice :

1) Certainly yes, probably by treating it like an object you serialize - VM instances can also be started with directives
which makes life a lot easier in some cases (heap size..)
2) Should be fairly easy to log the stacktrace somewhere
3) Certainly yes again, when catching an error in Java you can explicitely redirect the output, which is a bufferedoutputstream,
wherever you want - eg. to an outwards physical port you know you can listen to
4) Is it properly try-caught (the error)? Or is the output "saying" wether it failed or not and how maybe... have to check.
(but VM bugs happen, life's a bitch at times).
5) ...see my general purpose advice below.

Mobile devices are very different from desktop devices for that matter : you cannot really rely on OOP as it should be
and high level stuff, you have to understand the inner workings of the APIs in use to optimize properly.

To do this, you need a debug environment that allows you to easilly recover output, profile, etc.

My recommendation is the excellent, and free, Nokia J2ME development kit : it will allow you to test several architectures at once
for any app, to profile, stacktrace, etc... easilly.

Later on, this we, I will gather a few good references, links, etc. to get you started.

Seems I was -almost right- on many things, check these if you haven't nailed them already, they answer some of your questions :

http://www.hcilab.org/documents/tutorials/ImagePerformanceEvaluation/
http://developers.sun.com/mobility/midp/articles/picture/index.html
http://www.forum.nokia.com/document/Java_ME_Developers_Library_v2/GUID-00C29EFF-1A32-49D6-9AF4-0E5D8F1EE772.html

(Edited by argo navis on 08-03-2007 17:22)

i made a few javame demos a while back.

i used eclipse with the eclipseME plugin. it requires the WTK of course.

ok... I have made some progress... but still, this is a paint .

Does anybody have an idea how I can get more than 160xwhatever from my K700i? Apperantly it doesn't support anything but saying 'JPEG' to videcontrol.getSnapshot() - is there another function to capture images with?

Seems not, but.. "The video.snapshot.encodings system property contains a whitespace-delimited list. (of supported formats)".

That is the first thing, quoted from that page : http://developers.sun.com/mobility/midp/articles/picture/

Now, what is the goal you want to achieve, if it's possible to get a bit more into details?
I see numbers of ways "in theory" to achieve various goals : getting snapshots in the resolution you want
and image format you want sounds in my range of possibilities.

Using chuncks of a byte buffer to redirect the image to somewhere sounds feasible also, but I need to walk a bit in your shoes to tell more.

Well, System.getProperty('video.snapshot.encodings') returns the glorious
"JPEG".

Yes, no encoding=JPEG or the like, no 'multiple formats'... I don't even know if 'JPEG' is a valid string.


If I was able to get the picture in PNG, I could learn to decode that in just the parts I need, I hope .


Guess my best bet right now is to switch to a newer handheld.

Supposedly, if you pass "null" to that getSnapshot function, it should default to png. Supposedly.
Now, I don't know for the "i" version, but yesterday, I found other developers having the same problem
due to a firmware issue with the specified model... not the "i" version, the default version, but still..

Trying to upgrade the firmware before the device? And trying emulators bundled with the sdks? Noticed Sony/Ericsson
also offer a free dev kit.

great, the new handset arrived, and the bear walzes... it doesn't walz well yet, but it walzes never the less.

Still, I haven't found a way to redirect an exception stack trace to my special canvas...
stupid Exception class only has printStacktrace(), that writes to System.err - and that's declared final and has no method to redirect it!
(if this was 'real java' not 'java mobile edition' that would not be a problem).