Microsoft Bot framework allows you to integrate the bots in your custom applications be it web or Mobile. While for Web I was able to find some straight forward samples, unfortunately I couldn't find any sample for Integration of an android app.
Direct Line API allows you to communicate with your bot using the REST API or WSS (Web socket) based calls.
The API documentation is available here https://docs.botframework.com/en-us/restapi/directline3/
I wrote a very basic Android sample that shows a Chat like interface where you can send the messages to Bot and receive/render the response messages from Bot.
The Android code is available at my Github Repo
The code is written with synchronous REST API (ain't that a bada** way to write a sample code 🙂 ), I must change it to asynchronous and write a WSS based version of the same sometime soon.