Link Android Room Database with Firebase Realtime Database

After a lot of researches and looking desperately for an answer here's what I reached:

• Firebase already got a straight forward way to create the database and host it online. (I had my database already created so was trying to save time, but creating it from scratch using Firebase Realtime Database was a lot faster)
• Room Database is quite perfect if you are planning to save your database locally and offline (Up to the post date)

I think their is no need to connect your Room Database with Firebase Realtime database because,okay first try to solve this problem, why we use Room Database ?because when we don't have internet, we can get data from Room Database , no need of network... Firebase also provides offline mode , it can also save data in persistence, so why we use Room Database ?.. Hope you got the point...