Android bluetooth get connected devices

Question

How can I get a list of all connected bluetooth devices for Android regardless of profile?

Alternatively, I see that you can get all connected devices for a specific profile via BluetoothManager.getConnectedDevices.

And I guess I could see which devices are connected by listening for connections/disconnections via ACTION_ACL_CONNECTED/ACTION_ACL_DISCONNECTED...seems error prone.

But I'm wondering if there's a simpler way to get the list of all connected bluetooth devices.

Answer 1

To see a complete list, this is a 2-step operation:

1. get list of currently paired devices
2. scan for, or discover, all others in range

To get a list of, and iterate, the currently paired devices:

Set<BluetoothDevice> pairedDevices = BluetoothAdapter.getDefaultAdapter().getBondedDevices();
if (pairedDevices.size() > 0) {
    for (BluetoothDevice d: pairedDevices) {
        String deviceName = d.getName();
        String macAddress = d.getAddress();
        Log.i(LOGTAG, "paired device: " + deviceName + " at " + macAddress);
        // do what you need/want this these list items
    }
}

Discovery is a little bit more of a complex operation. To do this, you'll need to tell the BluetoothAdapter to start scanning/discovering. As it finds things, it sends out Intents that you'll need to receive with a BroadcastReceiver.

First, we'll set up the receiver:

private void setupBluetoothReceiver()
{
    BroadcastRecevier btReceiver = new BroadcastReciver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            handleBtEvent(context, intent);
        }
    };
    IntentFilter eventFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    // this is not strictly necessary, but you may wish
    //  to know when the discovery cycle is done as well
    eventFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
    myContext.registerReceiver(btReceiver, eventFilter);
}

private void handleBtEvent(Context context, Intent intent)
{
    String action = intent.getAction();
    Log.d(LOGTAG, "action received: " + action);

    if (BluetoothDevice.ACTION_FOUND.equals(action)) {
        BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
        Log.i(LOGTAG, "found device: " + device.getName());
    } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
        Log.d(LOGTAG, "discovery complete");
    }
}

Now all that is left is to tell the BluetoothAdapter to start scanning:

BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();
// if already scanning ... cancel
if (btAdapter.isDiscovering()) {
    btAdapter.cancelDiscovery();
}

btAdapter.startDiscovery();

Answer 2

That's how you get "connected" devices, not just paired devices. No need to check further state of it.

val btManager = view.getSystemService(BLUETOOTH_SERVICE) as BluetoothManager
val connectedDevices = btManager.getConnectedDevices(GATT)