OK... lets start from the begining...
what is your target platform.
(take a look on your phone, there should be an about option somewhere on it that will tel you all about the phone...)
for instance mine says
Copyright (c) 2003 Nokia. All rights reserved. Nokia and Nokia connecting people are registered trademarks of Nokia Corperation.
This product includes software licensed from Symbian Ltd. (c)Symbian Ltd 1998-2002. All rights reserved,
(folled by the picture of the Java coffee cup).
Java(tm) and all java-base marks are trademarks orregistered trademarks of Sun Microsystems, inc stac (r) LZS (r), (c)1996, Stac Inc, (c) 1994-1996 Microsoft Corperation. Includes one or more US patents: No...
when you know your target platform then you can decide on the technology to use.