This is Bluetooth state "Connected" or "Disconnected" notification giving Android app.
This app is one of the feature part of my project- "IoT Based Smart Inhaler for Context-aware service Provisioning". This app connected to the one devices via bluetooth and give notification as "Connected" when data is passing through the bluetooth. and give notification as "Disconnected" when data is passing is stop through the bluetooth or the device is out of range of bluetooth.