Implement the ListView Adapter, update the athlete class with all the infos to be shown, add a mechanism in the AthletesManager to notify the adapter when new data is available

[Ruggero1912]

In order to update the UI when new data arrives from the GATT clients:

• [x] implement the ListView Adapter
• [x] update the athlete class with all the infos to be shown
• [x] add a mechanism in the AthletesManager to notify the adapter when new data is available

A good mechanism for the notification could be a broadcast receiver (using LocalBroadcastManager) (but seems to be deprecated).

Otherwise consider this: https://developer.android.com/reference/androidx/lifecycle/LiveData

[Ruggero1912]

https://stackoverflow.com/questions/46207758/livedata-vs-handler-and-localbroadcast