Question

as someone’s who’s just starting to get into Android/Java programming, I’ve read the docs at https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#ACTION_DISCOVERY_FINISHED and i’m trying to figure out what whether I would only get ACTION_DISCOVERY_FINISHED when the bluetooth 12 second scan is completed, and it comes back WITH NO DEVICES, or, does it return ACTION_DISCOVERY_FINISHED every time it scans, and it has some sort of return code that I don’t see in the docs?

The scenario is: I’m building a broadcast receiver that would listen in to BT, and if it is turned on, starts discovery and ends discovery AND finds nothing, I wanna turn off BT.

If it does return codes, I would love a link/the codes themselves.

Thanks for reading and helping out!

Answer 1

The ACTION_DISCOVERY_FINISHED tells you that discovery has finished, no more or less.

There is a separate Intent, ACTION_FOUND, that is sent when a device is discovered.

To accomplish your desired functionality, you want to check in your broadcast receiver

intent.getAction().equals(BluetoothDevice.ACTION_FOUND)

If an intent is received such that this evaluates to true, then you have discovered a BluetoothDevice. If you want to do processing on that device, you can access it via

BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

Edit: If you only want to know that no devices were found, you can just set a flag in the ACTION_FOUND-handling code. If the flag isn’t set, then no devices were found.

EDIT2: The process of Bluetooth Device discovery will send out this sequence of intents:

1 ACTION_DISCOVERY_STARTED
0 or more ACTION_FOUND
1 ACTION_DISCOVERY_ENDED