Mobile Java Banking Applications

Mobile Java Application used for mobile banking are a great idea, but they do come with some few complexities. J2ME is great, the application is sandboxed on the device so there is little bit more security, the Java application will run on a number of handsets, they are written in java and not some obscure phone OS, but two issues in particular bother me.
Although the application is in Java and will run on a wide variety of handsets, there is a complexity firstly to make the user interface look 'nice' on different screen sizes and phone types. The Java APIs and classes on different handsets also differ so whenever your application does something that is not within the standard J2ME spec you are not sure whether it will work or not on all the handsets and this forces the application to be tested on every handset that you want to support. This is a huge overhead for testing and there does not seem to be a clear solution to the problem.

The second issue, particularly with banking applications is that to reduce network traffic you would like to save some data on the device. If you do this you have a big problem because users often change their phones. Even if there is a process to 'rebuild' this data from the server what happens to the data on the old phone. It is not likely that the average user would delete the application and therefore this data could get into the wrong hands. If no data is stored on the phone then you do not get much gain over using J2ME vs simply using the phone's web browser.