Combining two java programs..

I just want to ask how can I combine two programs and put it in one program.. I have this game with 2 players capability and another game client with just random AI.. Is there any way to combine those two? I dont have much time rewriting the codes..

On the main program, i have sub menu for single player.. but I dont know how to import another program when they click the single player menu..

Could you give me examples.. Thanks!

There is no generic way to do this as it will depend on the specifics of the code, and so I don't think anyone can give you specific advice given the information at hand.