Android Studio - Sending a Bluetooth PIN automatically

Question

I am looking at the following code by Lorensius W. L. T

I have seen other posts about sending a PIN automatically (e.g. 1234) to the device when it pairs so that there is no user prompt. I can't figure it out how to add their code fragments to get it to work.

How is the following code modified to achieve this?

/**
 * Device list.
 * 
 * @author Lorensius W. L. T <lorenz@londatiga.net>
 *
 */
public class DeviceListActivity extends Activity {
    private ListView mListView;
    private DeviceListAdapter mAdapter;
    private ArrayList<BluetoothDevice> mDeviceList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_paired_devices);

        mDeviceList     = getIntent().getExtras().getParcelableArrayList("device.list");

        mListView       = (ListView) findViewById(R.id.lv_paired);

        mAdapter        = new DeviceListAdapter(this);

        mAdapter.setData(mDeviceList);
        mAdapter.setListener(new DeviceListAdapter.OnPairButtonClickListener() {            
            @Override
            public void onPairButtonClick(int position) {
                BluetoothDevice device = mDeviceList.get(position);

                if (device.getBondState() == BluetoothDevice.BOND_BONDED) {
                    unpairDevice(device);
                } else {
                    showToast("Pairing...");

                    pairDevice(device);
                }
            }
        });

        mListView.setAdapter(mAdapter);

        registerReceiver(mPairReceiver, new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED)); 
    }

    @Override
    public void onDestroy() {
        unregisterReceiver(mPairReceiver);

        super.onDestroy();
    }


    private void showToast(String message) {
        Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();
    }

    private void pairDevice(BluetoothDevice device) {
        try {
            Method method = device.getClass().getMethod("createBond", (Class[]) null);
            method.invoke(device, (Object[]) null);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void unpairDevice(BluetoothDevice device) {
        try {
            Method method = device.getClass().getMethod("removeBond", (Class[]) null);
            method.invoke(device, (Object[]) null);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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

            if (BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {             
                 final int state        = intent.getIntExtra(BluetoothDevice.EXTRA_BOND_STATE, BluetoothDevice.ERROR);
                 final int prevState    = intent.getIntExtra(BluetoothDevice.EXTRA_PREVIOUS_BOND_STATE, BluetoothDevice.ERROR);

                 if (state == BluetoothDevice.BOND_BONDED && prevState == BluetoothDevice.BOND_BONDING) {
                     showToast("Paired");
                 } else if (state == BluetoothDevice.BOND_NONE && prevState == BluetoothDevice.BOND_BONDED){
                     showToast("Unpaired");
                 }

                 mAdapter.notifyDataSetChanged();
            }
        }
    };
}