It always depends on the operating system of the cell phone. Android apps are mostly written in Java programming language . while most mobile devices run symbian and most symbian programmings are C++.
Havent said that, there are basically two types of programming languages- the more common are Java script language which runs ".jar" files. The modern and complicated symbian sis rogramming runs "old.jar files as well as new file types ".sis". Thus symbian help in faster and easier data management. Eg Nokia N-series and E-series use symbian sis programming.