Here is the screenshot of a main screen.
Please create 2 fully working screens.
API first screen and
API second screen
for both of them you need to authorize.
I am getting all the data by retrofit2.
For "channels" (list of chats) use TabLayout, ViewPager,
with fragment RecyclerView (with customized RecyclerView.Adapter) inside ViewPager.
Fragment has list of custom items.
Tabs in TabLayout are also customized, as you see.
For list of messages I use simple ListView with customized BaseAdapter.