unread message message counter in firebase

[Abhi]

Hai all....

I am developing an app that enables private chat with my customers and sellers using android studio and firebase. I was successful in implementing the functionalities. I want to add in-app notifications (not push notifications) in my app like WhatsApp (as shown in the red circle in the figure). I like to show the last unread message on the top with the count. I had used linear layout manager.setReverseLayout(true), to sort the messages, so that messages will be sorted based on date, but I didn't get the functionality to display unread messages count inside the app. Most of the literature deals with unread messages count on the app icon badge  and about push notifications not on in app . I don't want push notifications using SMS. If some know how to get an unread message count inside the app itself, please help .