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George Kalfas

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since Aug 05, 2004
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Recent posts by George Kalfas

Just to answer this question for future reference, it seems that progressive jpegs are not yet supported.I've found many jpeg decoders but none claimed that it could render a progressive jpeg. I have tested many ways of displaying a progressive jpg but the picture just appeared all at once.

In order to test it yourself you must find a progressive picture that is smaller than your display, cause if it is larger the browser only gets the first (less detailed) layer anyway.
14 years ago
Hey to you all!!

I'm wondering if the primitive types of Java Micro are the same ( in terms of range and byte size ) as traditional java (a.k.a. int 4 bytes, double 8 bytes etc...). I'm talking about the CLDC 1.1 configuration which supports floating points.
I've searched the CLDC documentation and found out that for instance floating data types follow the IEEE 754 configuration which is the same that J2SE follows. To my mind this means that the primitive data types are the same in both J2ME and SE.
Anybody can confirm that???

Thank you all in advance!
14 years ago
Although you are able to send an SMS from inside your Midlet, your Mildet uses your phone's native methods to transmit it and so the SMS eventyaly passes through your mobile services provider and so you get charged.
14 years ago
Greetings to everybody!

I'm writing a midlet that at some point downloads an image from the web. The image is quite large and I'm wondering whether exists a library that can read and render progressive JPEG files. I've searched the net but I could not find an answer to that...

Thank you in advance!
14 years ago
Greetings to all!

I have a question about the built-in browser, when it is called using the command.
I'm trying to view some very simpe HTML pages that I created, and I was thinking instead of making my own HTML parser, to use the built in browser of the mobile.
But when the browser is running it maps the command buttons with its own default settings(refresh, enter URL, exit browser etc.), and as it seems I have no control over the functionality that it offers.
So my question is : is ti possible somehow to customize the mobile browser, so I can map my own custom functionalities on the command buttons?
And generally is it possible to have any level of control over the native browser???

Thank you all very much and in advance for your answer!
15 years ago
Dear Syam,

Thank you very much for your reply! What you said actually worked!
As it turns out here in Greece the providers also give Internet access through GPRS.
But I would like to ask you something. I tried to transmit a 50kb image to the server and it took about 31 seconds. From this fact I conclude that the data rate is about 12,6 kbps. Is this rate normal for GPRS tranmsissions?

Data service here in greece is supposed to be 56k on non 3g networks and up to 1,8Mbps in 3g networks.
So I guess that if I pay for data service I sould normally expect better performance, am I correct??
15 years ago
Greetings to you all!!

I've read all the articles that Shoumin posted and I was very disturbed by what I've learned from them. Signing is necessary ofcourse, but transforming this need into a money making machine is just a shame! Especially for Sun( I expected something like that from the manufacturers!!).

Well I have two quick questions:
1)I've read some posts in other forums that it is possible to hack some phones so that they trust every application, and never ask permission. Is this a fact or a myth? In my project I need to use a Nokia n95 phone, owned by a relative, and my midlet's only being developed especially for that phone. If I could hack it that would suit me better than paying 240$ to Java verified...

2)If you download somehow a trusted midlet, is the key contained in the jar or the jad file?

Thank you in advance!!
15 years ago
Dear all!

First of all I have used Rajesh's advice and created a bufferedInputStream, which in turn with the use of tha availiable() method returns zerol.So it says that the InputStream does not provide any bytes what so ever.

And to answer your question Ben the file does not exist on the linux box.
I'm trying to upload an Image from a mobile device to the server(linux box). The file is created on the server (which means that my wireless toolkit emulator communicates with the remote machine), but the file does not contain any data ( which means that although the server receives the request, it does not receive any bytes).

In case this helps this is my midlet code:

[ August 18, 2007: Message edited by: George Kalfas ]
15 years ago
First of all, I would like to thank you all for your so quick responses to my problem!

Ben, I tried the solution you advised(set the absolute path), but unfortunately it didn't solve my problem, expept from the fact that now the file image.png is created in a different folder, but is still null...

Now I'm a new to this but I think that the source of the problem is (as I mentioned in my original post) that the following loop

while ((len = > 0)
bos.write(buf, 0, len);

is never entered. This means that returns 0 , which in turn means that no data is read, right?

Is there any reason why the InputStream does not receive anything on the remote machine, but receives normally on the localhost? Does it have anything to do with the fact that it is remote? Or is there a difference between Windows tomcat and Linux tomcat, regarding the configuration? Or is there some sort of problem with the permissions?

Thank you all very much! I hope I have not tired you much!

PS: The catalina.out file does not provide information about an error or something similar...
PS2: If this question does not violate any forum rule can you recommend me of a good book on servlets? I am a J2me developer my self but it seems that I have to learn more about servlets now... Thank you!

[ August 16, 2007: Message edited by: George Kalfas ]
[ August 16, 2007: Message edited by: George Kalfas ]
15 years ago
Thank you very much Tim!!You've been very helpful!Again!
15 years ago
Greetings to everybody!

I don't know whether this is the right place to post this topic since it concerns both servlets and j2me. If this post does not belong here please place it where it does!

I've recently began developing j2me applications, and lastly I've written a Midlet that transmits a png image file to a server.
The server side software is based on apache tomcat 6.
I've installed tomcat on two pcs. One laptop with windows where I do my developing, and one linux machine (ubuntu to be exact) with static ip which is designated to be the server when my project ends. I've placed the same web.xml,context.xml,server.xml and tomcat-users.xml to both servers so I assume that they are configured exactly the same.

I've written a very simple servlet that receives the Image through an input stream. The code is the following :

When I execute my Midlet through the Wireless Toolkit emulator and I target my request to the tomcat that runs on localhost (the windows machine) the application works perfectly.

I've transfered this servlet to the linux machine, changed the following code to recompiled it there and tried it out, but the servlet now does not work.
A image.png file is created but it is empty. After running some tests I discovered that this loop
is never entered when it runs on the linux machine. Can anyone figure out why the InputStream receives nothing when ran on the pc with the static ip, but runs perfectly on the localhost? The Mildet is the same on both occasions.

Any help would be greatly appreciated! I hope you haven't slept half way through this post!

Thank you a lot and in advance for your reply!
15 years ago
Ilker ilker, do not be afraid to show your real name in here...It is not an astrology forum!!
Everybody uses their real names.
I've been here for three years or so with my real name and I was never bothered by anyone.

I hope you find the answer you are seeking!
[ August 12, 2007: Message edited by: George Kalfas ]
15 years ago
I would recommend the following:
Good knowledge of Data types and streams. More than basic knowledge of AWT(it will help you understand the ways that things are drawn in J2ME like Forms or Canvas) and good knowlegde of threads.

The rest you will find out along the way!
Good luck!!
15 years ago
Greetings to all!

I've recently written a Midlet that tries to transmit a png image to a server that runs on Apache Tomcat. My Midlet uses an HTTP connection.
When I use the emulator of the wtk everything works fine. But when I use the the Midlet from my mobile, the response I get is a xml page that tells me that my network settings do not allow me to request such a URL ( or something like that, I don't remember exactly). This xml page does not seem to be coming from my apache.

So my question is do I need a special service from my local Mobile Service provider in order to be able to transmit data from my mobile? I'm currently living in Greece and I'm using Vodafone as my service provider. My mobile is able to tranmsit MMSs and I am able to view WAP pages and stuff.

Here in Greece, mobile service providers offer a service that is called "Data Service", but as far as I know it is mainly used to access the Internet through your laptop. They give you a SIM card which you place inside a modem of some sort that hoooks on youn PCIMCIA slot. Is this what I need maybe?

If anybody knows how to transmit data in the real world and has some knowledge of the services offered by the providers I would deeply appreciate a reply!

Thank you very much and in advance!
15 years ago