Why can't I view and connect to a Bluetooth LE device? (Android)

Question

I've been working on this for a while and putting together code from multiple sources over the net, however I'm still not getting any results.

Initially I was trying to scan for BLE devices and view them in the overflow menu and connect from there, but couldn't get that to work...

Now I have attempted to use a list view for the devices, but still no luck. I'm v new to this so not entirely sure what links to what. I can initiate a scan using startDiscovery and nothing crashes - but no luck.

I'll try provide as much code as possible, however I don't know where the problem lies. This is a university assignment.

I've tried adding a BroadcastReceiver but that hasn't changed anything I'm meant to be connecting to a SensorTag device and receive some sensor readings via GATT connection - I've already added code for this but I don't think it plays a part in the connection process so I haven't included it.

@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_scan);
  vHandler = new Handler();

  BluetoothManager manager = (BluetoothManager) getSystemService(BLUETOOTH_SERVICE); // access bluetooth manager
  vBluetoothAdapter = manager.getAdapter();

  vTags = new ArrayList < BluetoothDevice > (); // store bluetooth devices


  // Initialise list view adapter
  ListView vListView = (ListView) findViewById(R.id.list);
  vLeDeviceListAdapter = new LeDeviceListAdapter();
  vListView.setAdapter(vLeDeviceListAdapter);

  IntentFilter vfilter = new IntentFilter();
  vfilter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
  vfilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
  vfilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
  vfilter.addAction(BluetoothDevice.ACTION_FOUND);

}


//Device Scan Callback
private BluetoothAdapter.LeScanCallback vLeScanCallback =
  new BluetoothAdapter.LeScanCallback() {

    @Override
    public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
      runOnUiThread(new Runnable() {
        @Override
        public void run() {
          vLeDeviceListAdapter.addDevice(device);
          vLeDeviceListAdapter.notifyDataSetChanged();
        }
      });

      Log.i(TAG, "New LE Device: " + device.getName() + " @ " + rssi);
    }
  };


private void scanLeDevice(final boolean enable) {
  int SCAN_PERIOD = 10000;

  if (enable) {
    // Stops scanning after a pre-defined scan period.
    vHandler.postDelayed(new Runnable() {
      @Override
      public void run() {
        vScanning = false;
        stopScan();
        invalidateOptionsMenu();
      }
    }, SCAN_PERIOD);
    vScanning = true;
    startScan();
  } else {
    vScanning = false;
    stopScan();
  }
  invalidateOptionsMenu();
}


// Adapter for holding devices found through scanning.
private class LeDeviceListAdapter extends BaseAdapter {
  private ArrayList < BluetoothDevice > vLeDevices;
  private LayoutInflater vInflator;

  LeDeviceListAdapter() {
    super();
    vLeDevices = new ArrayList < > ();
    vInflator = Activity_Scan.this.getLayoutInflater();
  }

  void addDevice(BluetoothDevice device) {
    if (!vLeDevices.contains(device)) {
      vLeDevices.add(device);
    }
  }

  public BluetoothDevice getDevice(int position) {
    return vLeDevices.get(position);
  }

  void clear() {
    vLeDevices.clear();
  }

  @Override
  public int getCount() {
    return vLeDevices.size();
  }

  @Override
  public Object getItem(int i) {
    return vLeDevices.get(i);
  }

  @Override
  public long getItemId(int i) {
    return i;
  }

  @Override
  public View getView(int i, View view, ViewGroup viewGroup) {
    ViewHolder viewHolder;
    // General ListView optimization code.
    if (view == null) {
      view = vInflator.inflate(R.layout.listitem_device, viewGroup, false);
      viewHolder = new ViewHolder();
      viewHolder.deviceAddress = (TextView) view.findViewById(R.id.device_address);
      viewHolder.deviceName = (TextView) view.findViewById(R.id.device_name);
      view.setTag(viewHolder);
    } else {
      viewHolder = (ViewHolder) view.getTag();
    }

    BluetoothDevice device = vLeDevices.get(i);
    final String deviceName = device.getName();
    if (deviceName != null && deviceName.length() > 0)
      viewHolder.deviceName.setText(deviceName);
    else
      viewHolder.deviceName.setText(R.string.unknown);
    viewHolder.deviceAddress.setText(device.getAddress());

    return view;
  }
}

static class ViewHolder {
  TextView deviceName;
  TextView deviceAddress;
}

Answer 1

You need to enable location settings to view nearby BLE devices. You can either request runtime location permission or enable it manually.