I would be guessing you want to play some Java game you play on a web page on your PC offline. To do that would take a few mildly advanced steps. You either get the .JAR they used or just save the page for later offline use.
There is no such software to convert since my bet is it's done with the old fashioned this or that way.
Bob
Hey there. I'm looking for a software that let me convert Java games offline. But I couldn't search it somewhere at cnet.com or at Google. Does anybody find the link of the software that can convert Java games to Java games offline? If so then juse let me know.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic