How to know if a bluetooth device is online with it's address?

Question

I am getting list of all paired devices by using method bluetoothAdapter.getBondDevices() . Is there anyway to check how many devices are actually online ie ready to receive data?

Answer 1

What I'm doing in my app is to create BroadcastReceiver, and implement onReceive(), where I'm checking for BluetoothDevice.ACTION_FOUND and adding discovered devices to a list:

//holds names of BT devices discovered
private ArrayList<String> btDevices = new ArrayList<String>();

In onCreate(), create receiver:

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            if (device.getName() != null) {
                btDevices.add(device.getName());
            }
            else {
                Log.d("MyTag", "device.getName() is null");
            }
        }
    }
};

Then, create intent filter and register receiver:

IntentFilter btFilter = new IntentFilter();
btFilter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
btFilter.addAction(BluetoothDevice.ACTION_FOUND);

registerReceiver(mReceiver, btFilter);

Get bluetoothAdapter and start discovery:

bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

//we have adapter
if (bluetoothAdapter != null) {
    //Bluetooth is OFF, so turn it on
if (!bluetoothAdapter.isEnabled()) {
        bluetoothAdapter.enable();      
    }
    else {
        bluetoothAdapter.startDiscovery();
    }
}

Then, I can check how many devices have been discovered with btDevices.size()