J2ME and JAR creation

[skarosi]

Hi all,
I am quite new to the J2ME enviroment, i actually just did my first hello world aplication.
I am working on the wireless toolkit from sun and i was wantering how is it possible to load this application to my mobile phone? do i have to create a jar file? if yes how?
thanks a lot
ilias

 

[boxracketts]

Yes you have to create a JAR and a JAD file,load up these to your phone and then install the JAD.

When using the wireless toolkit you create these files - see: "The bin directory contains the compiled MIDlet suite (a .jar file) and the MIDlet suite descriptor (a .jad file)" in the link:

http://developers.sun.com/mobility/midp/articles/wtoolkit/

You copy the JAR and JAD files onto your phone by one of these methods:
1) bluetoothing both files from your PC to the phone
2) downloading from your PC via a USB cable to the phone
3) uploading these files to a web site and via the phone's browser downloading to the phone.

Install your "HelloWorld" application by opening the JAD file which in turns installs the JAR file. If you have a problem with the JAD you can install using the JAR. You might have to change the settings on your phone to allow installing without a certificate - it will prompt you to ask if you want to install from this untrusted source.

If you have seen it then Netbeans 5.5 IDE is excellent for creating J2ME midlets:

http://www.netbeans.org/products/ide/

You also add to this:

http://www.netbeans.org/products/mobility/

 

[skarosi]

The problem is that i can find how i can create the Jad file. I figured out how to make the jar, i did it and sent it to my nokia phone, but it says that it is an invalid application.
would u have any idea why?
thanks

 

[boxracketts]

Invalid file is common - often due to:
1) you are trying to install an unsigned application when your phone options dictate only signed - ie with certificate. Change your phone options to allow unsigned applications.
2) Your midlet or any associated images are too big - depends on the phone
3) a bluetoothed JAD/JAR file gets corrupted - I found sometimes that a bluetoothed JAD/JAR (in my case from linux using OBEX) throws this message. Solution is to transfer the JAD/JAR by USB cable.

some questions:
What phone are you using?
How big is your midlet?

 

[skarosi]

I tried it with two phones, Nokia 5200 and Nokia 6600, both using bluetooth, since i dont have a cable.
The program is prety small, just the helloworld example. that is 1,42KB.

Do you know a good site that i can find out about the commands? I want to start making programs of my own, just to learn it, but i have no idea of the commands. for example, how can i read something from the keyboard?

thanks

 

[boxracketts]

Have a look at this J2ME tutorial which shows you how to handle the user interface:

http://today.java.net/lpt/a/187

JAD file
Netbeans IDE 5.5 creates a JAD automatically alongside the JAR or you can create a JAD manually in an editor, see:

http://en.wikipedia.org/wiki/JAD_(file_format)

here's an example:
MIDlet-Name: MyFirst
MIDlet-Version: 1.0.0
MIDlet-Vendor: Sun Microsystems, Inc.
MIDlet-Description: My First MIDlet
MIDlet-Info-URL:

http://java.sun.com/j2me/

MIDlet-Jar-URL: first.jar
MIDlet-Jar-Size: 1063
MicroEdition-Profile: MIDP-1.0
MicroEdition-Configuration: CLDC-1.0
MIDlet-1: MyFirst,, FirstMIDlet


Your JAR size is small so no problem there.


You can check out your phones at:

http://www.j2mepolish.org/devices/devices-vendor.html#Nokia

I notice that Nokia 5200 is MIDP 2.0 CLDC 1.1 while Nokia 6600 is MIDP 2.0 though CLDC 1.0 - your JAD and manifest within the JAR needs to reflect these.

 

[boxracketts]

also have a look at this for a visual flow development of a midlet:

http://www.netbeans.org/kb/50/quickstart-mobility.html