Bluetooth Low Energy Rssi Android

Question

I am developing an application where I have to connect to Bluetooth Low Energy device on Android 4.3. I tried this to display the rssi in my app but It doesn't work

@Override
            public void onLeScan(final BluetoothDevice device, final int rssi, byte[] scanRecord) {
                //final LeDeviceListAdapter deviceLe = new LeDeviceListAdapter(device, rssi, scanRecord);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {

                        mLeDeviceListAdapter.addDevice(device,rssi);
                        mLeDeviceListAdapter.notifyDataSetChanged();

                    }
                });

my list adapter code is :

private class LeDeviceListAdapter extends BaseAdapter {
    private ArrayList<BluetoothDevice> mLeDevices;
    private LayoutInflater mInflator;

    public LeDeviceListAdapter() {
        super();
        mLeDevices = new ArrayList<>();
        mInflator = MainActivity.this.getLayoutInflater();
    }

    public void addDevice(BluetoothDevice device) {
        if (!mLeDevices.contains(device)) {
            mLeDevices.add(device);

        }
    }

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

    public void clear() {
        mLeDevices.clear();
       // notifyDataSetChanged();
    }






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

    @Override
    public Object getItem(int i) {
        return mLeDevices.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 = mInflator.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);
           // viewHolder.signal = (TextView) view.findViewById(R.id.device_signal);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }

        BluetoothDevice device = mLeDevices.get(i);
        //final String rssi_s=device.getRssi();
        final String deviceName = device.getName();
       /* ScanResult rssi=null;
        final double rssi_s = rssi.getRssi();
        String rssiString = String.valueOf(rssi_s);*/
        //final String rssiString =getString(valueOf(rssi_s));
        if
            (deviceName != null && deviceName.length() > 0){
            viewHolder.deviceName.setText(deviceName);
           // viewHolder.signal.setText(rssiString);

        }
        else
            viewHolder.deviceName.setText(R.string.unknown_device);
            viewHolder.deviceAddress.setText(device.getAddress());




        return view;

    }
}


// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {

            @Override
            public void onLeScan(final BluetoothDevice device, final int rssi, byte[] scanRecord) {
                //final LeDeviceListAdapter deviceLe = new LeDeviceListAdapter(device, rssi, scanRecord);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                       // String rssi_signal=String.valueOf(rssi);


                        mLeDeviceListAdapter.addDevice(device);
                        mLeDeviceListAdapter.notifyDataSetChanged();

                    }
                });
            }
        };

static class ViewHolder {
    TextView deviceName;
    TextView deviceAddress;
    //TextView signal;
}

Do you have any idea how I can display this ? do I still have to type this in my oncreate method?

mLeDeviceListAdapter=new LeDeviceListAdapter();

Answer 1

Your problem is (1) that the adapter itself does not have a method for tracking the RSSI value and (2) your adapter's list item view has no way to show the RSSI value and the adapter it self does not have a method for tracking the RSSI value. Here are the problems in detail:

Problem 1 The list adapter is not capable of tracking the RSSI value.

You are adding the device and RSSI value to the adapter with this call:

mLeDeviceListAdapter.addDevice(device,rssi);

BUT the adapter only has a method like this:

public void addDevice(BluetoothDevice device) {
    if (!mLeDevices.contains(device)) {
        mLeDevices.add(device);

    }
}

As you can see the methods do not match. I would propose doing the following: First create a new class that will hold both the BluetoothDevice and the RSSI value. Something like this:

private class LeScanRecord {
    public final BluetoothDevice device;
    public final int rssi;

    public LeScanRecord(BluetoothDevice device, int rssi) {
        this.device = device;
        this.rssi = rssi;
    }
}

Then change you adapter to accept track instances of the new class (note that this addressed Problem 2 by filling in the text field with the RSSI value):

/**
 * Adapter for the scan record devices
 */
private class LeDeviceListAdapter extends ArrayAdapter<LeScanRecord >
{
    /**
     * View inflater
     */
    private final LayoutInflater inflater;

    public LeDeviceListAdapter ()
    {
        super(MainActivity.this, R.layout.listitem_device);
        inflater = MainActivity.this.getLayoutInflater();
    }
    @Override
    public void add(LeScanRecord object)
    {
        for (int i = 0; i < getCount(); i++)
        {
            if (getItem(i).device.equals(object.device))
            {
                return; // do not add duplicates
            }
        }
        super.add(object);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        ViewHolder viewHolder;
        // General ListView optimization code.
        if (view == null) {
            view = mInflator.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);
            viewHolder.rssi= (TextView) view.findViewById(R.id.device_signal);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }

        LeScanRecord record = getItem(position);
        final String deviceName = record.device.getName();
        if (deviceName != null && deviceName.length() > 0){
            viewHolder.deviceName.setText(deviceName);

        }
        else {
            viewHolder.deviceName.setText(R.string.unknown_device);
        }
        viewHolder.deviceAddress.setText(record.device.getAddress());
        viewHolder.rssi.setText(Integer.valueOf(record.rssi));


        return view;
    }
}

static class ViewHolder {
    public TextView deviceName;
    public TextView deviceAddress;
    public TextView rssi;
}

The last thing to do is add instances of the scan record to the adapter. So change:

@Override
public void onLeScan(final BluetoothDevice device, final int rssi, byte[] scanRecord) {
    //final LeDeviceListAdapter deviceLe = new LeDeviceListAdapter(device, rssi, scanRecord);
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            mLeDeviceListAdapter.addDevice(device,rssi);
            mLeDeviceListAdapter.notifyDataSetChanged();

        }
    });
}

To:

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

        }
    });
}