Chat room with chat bubbles in Android Studio

I need a chat room that will be part of an application, I need the functionality so I can add that to the application. It should be possible for the users to chat with each other and have group chats.
I want it to be like in this example, a view which displays a list of channels for a user to select and viewing the different channels:
https://medium.com/swlh/android-chat-bubbles-building-ios-style-chat-in-android-819757a4e691.

I want you to use Android Studio and use Java as the programming language.