I am making a chat app for android. Where i have use SMACK library and also I have use omemo for message encryption. I can generate, encrypt and send - receive message to other user. But I am unable to generate fingerprint for MUC means group chat.
You don't have to "generate fingerprint" for MUC usage. OMEMO uses the same identity keys for MUC as are used in one-to-one chats. Basically a message to a group chat is simply encrypted for each and every recipient.
Sorry code sample is not possible because of secrecy. But i can give some hints.
You are aware of the fact that smack-omemo-signal is licensed under GPLv3, right? ;)