I have created a Space Invaders Game using an example game + source. Using the existing source I have spent 3 days coding the game and spent 4 days trying to get it to run on a mobile phone.
The runnable jar file works on my PC but not on a mobile phone.
You can't run J2SE applications on mobile phones that only support J2ME. It is also not easy to port such an application to J2ME because Canvas
in MIDP is different and very limited.