No way to download working java games onto a D800?

I have transferred .jar and .jad files to my samsung d800 but when I
try to run
them, I always get an 'unsupported file type' error message. I have
googled around for a solution but am at a loss. I thought there
could be a problem with the java on my phone but the games that came
with it work ok and they are presumeably also java flash games.
I have transferred the files from my pc using a usb cable and pcstudio
but I have also downloaded many other files from web sites using wap
and neither of these methods work.
I am coming to the conclusion that there is no way to get new games on
this phone and if this is true then it is quite a backward step.
Has anyone managed to do this?

> I have transferred .jar and .jad files to my samsung d800 but when I
> try to run them, I always get an 'unsupported file type' error message.

I might be barking up the wrong tree here, but is the phone locked to
a particular network ?

IIRC networks can lock out the use of java not downloaded from their
network (at a fee)