What programming language do I have to learn to be able to design mobile applications for nokia, blackberry, adroid etc?

Different devices have programming languages they support. Here's a brief list:

All Nokia support Java, some support symbian.
All BB's support Java but BB has its own language.
Android is a language and runs on Android phones.
Xcode is a language that runs on iphone.
There's also Bada language for samsung.

The list is endless, choose the device you want to develop for and learn the language.

For a beginner I suggest going the Java way. If you don't understand Java Standard Edition, learn that first. You can then decide to choose one of the options above.

Developing for android requires a good knowledge of Java before proceeding, so learning Java is still best.

Can someone post a simple tutorial on how to start j2me? How to bundle the code and send to mobile, so it actually installs??

@OP  for the three you mentioned, Java.

Number_One:

Different devices have programming languages they support. Here's a brief list:

All Nokia support Java, some support symbian.
All BB's support Java but BB has its own language.
Android is a language and runs on Android phones.
Xcode is a language that runs on iphone.
There's also Bada language for samsung.

The list is endless, choose the device you want to develop for and learn the language.

--> Symbian is an operating system and not a language! If you are good enough in C++ then you good enough to start developing apps or wateva for the symbianOS. For a nokia phone that supports java, well obviously Java is the key
--> Yes the blackberry mobile phone supports Java but it ain't gat some special language. It just has a few extra packages added to the Java API.
--> Android is again like Symbian and blackberry, its an OS. However, it supports Java as its main programming languae but i think it somehow supports C/C++(dnt really knw much about developing android apps with c/c++)
--> XCode is NEITHER a programming language nor an OS. Its more like an IDE(like netbeans or eclipse). However, you develop and build iOS apps on XCode using the Objective-C language. There are others ways for developing apps for the iOS too like flash.

Can someone post a simple tutorial on how to start j2me? How to bundle the code and send to mobile, so it actually installs??

You can download this book (not written by me). It helped me when I first started JavaME. Download from http://www.greenspek.com/download/INTRO.pdf. While you are there, you can visit http://www.greenspek.com/download to see some Java and BB apps I've done (just to encourage you).

--> Symbian is an operating system and not a language! If you are good enough in C++ then you good enough to start developing apps or wateva for the symbianOS. For a nokia phone that supports java, well obviously Java is the key
--> Yes the blackberry mobile phone supports Java but it ain't gat some special language. It just has a few extra packages added to the Java API.
--> Android is again like Symbian and blackberry, its an OS. However, it supports Java as its main programming languae but i think it somehow supports C/C++(dnt really knw much about developing android apps with c/c++)
--> XCode is NEITHER a programming language nor an OS. Its more like an IDE(like netbeans or eclipse). However, you develop and build iOS apps on XCode using the Objective-C language. There are others ways for developing apps for the iOS too like flash.

Thanks for sorting that out.