By your description it is not clear what is your task at all and what are points with which you stuck.
Switching to java will be of benefit only if you know java better then python. Both systems allow do almost anything, but in different ways (sometimes slightly different, sometimes totally different). In both languages you will not find anything like:
myRpg = new RpgGame();
And if you have already part of the job done, then there are far fewer reasons for switching anyway.