This is a post copied from another forum:
I haven't tried it myself, but good luck!
Many people have asked, "can i play java (j2me) games on my computer?"
the answer is..."YES"
This is how you do it:
First of all, you will need Java 2 Platform, Standard Edition, v 1.4.2 (J2SE)
you will find mirrors to the download here:
Next, you will need to get the software that lets you play the j2me apps (the mobile java apps) J2ME Wireless Toolkit 2.1
you will need to register to download here:
takes about 2 minutes, pretty simple
now when u install that, it will ask you where the virtual machine is, if u installed the previous software by default settings, it should be here:
now, you are almost good to go
now to run the game, u will need to run the *.jad file, u cant run the *.jar file
to make the *.jad file if you dont have it already, download this software
here is an example of what youd type in:
if you saved a game called "game.jar" to the C drive, you will type in:
now you can play the *.jad file in the software called "Run MIDP Application ..." in the folder called "J2ME Wireless Toolkit 2.0_01"
There is also an emu for N-Gage. You can order it here (yes, you will have to pay for it).