Android蓝牙连接错误

Question

I'm developing a bluetooth app to control an Arduino board, but now I made some mistakes: when I try to make a connection from my phone, it displays an AlertDialog (it is OK) and a lot of Toasts (they're called from onSensorChanged ). The BT module connected to the board is OK (tested with other apps), so the problem is Java: I can't make a connection to my BT module. Unfortunately, Android Studio doesn't give me any logcat or errors. This is my code:

/* imports... */
public class MainActivity extends AppCompatActivity implements SensorEventListener {

    /* Bluetooth */
    private static final int REQUEST_ENABLE_BT = 1;
    private String selectedDevice = "";
    static final UUID defaultUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");    //This SPP UUID should work for most devices.
    //private boolean isConnected = false;
    BluetoothAdapter bluetoothAdapter;
    BluetoothSocket bluetoothSocket;

    /* Is in full screen = ? */
    private boolean FullScreenState = true;

    /* Views */
    private SeekBar steeringWheel;
    private SeekBar forwardsSpeed;
    private SeekBar backwardsSpeed;
    private Toolbar toolbar;
    /* Dialogs */
    AlertDialog.Builder errorDialog;
    AlertDialog.Builder listDialog;
    ProgressDialog progressDialog;

    /* Accelerometer managers */
    Sensor accelerometer;
    SensorManager sensorManager;
    float Y = 0;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        (...)

        /* Views */
        steeringWheel = (SeekBar) findViewById(R.id.Steering_wheel);
        forwardsSpeed = (SeekBar) findViewById(R.id.Forwards_speed);
        backwardsSpeed = (SeekBar) findViewById(R.id.Backwards_speed);
        /* listDialogs */
        listDialog = new AlertDialog.Builder(this);
        listDialog.setCancelable(true);
        listDialog.setTitle(R.string.app_name);
        //listDialog.setMessage("Select a device:");
        listDialog.setIcon(R.drawable.launcher_icon);
        //listDialog.setView(devicesListView);
        listDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        /* errorDialog */
        errorDialog = new AlertDialog.Builder(this);
        errorDialog.setCancelable(false);
        errorDialog.setTitle(R.string.app_name);
        errorDialog.setIcon(R.drawable.error_material);
        errorDialog.setPositiveButton("I got it", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

        /* Set the full screen and keep the screen always on... */
        /* Accelerometer initializer... */
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        ...
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        ...
        if (id == R.id.toolbar_connect) {
            initializeBT();
            return true;

        } else if (id == R.id.toolbar_settings) {
            /* Settings activity. Coming soon. */
            return true;

        } else if (id == R.id.toolbar_disconnect) {
            if (bluetoothSocket != null) {
                try {
                    bluetoothSocket.close();

                } catch (IOException e) {
                    errorDialog.setMessage("Disconnection error!");
                    errorDialog.show();
                }
            }
            return true;
        }
    ...
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        /* Get the axes */
        Y = event.values[1];

        /* Set the steering wheel position */
        steeringWheel.setProgress((int)Y + 10);
        send(String.valueOf(steeringWheel.getProgress()));
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        ...
    }


    private class connect extends AsyncTask<Void, Void, Void> {

        private boolean connectionSuccess = false;

        @Override
        protected void onPreExecute() {
            progressDialog = ProgressDialog.show(MainActivity.this, "Connecting...", "Creating bluetooth connection");
        }

        @Override
        protected Void doInBackground(Void... devices) {
            try {
                if (bluetoothSocket == null) {
                //if ((bluetoothSocket == null) || (!isConnected)) {
                    bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
                    BluetoothDevice arduino = bluetoothAdapter.getRemoteDevice(selectedDevice);
                    bluetoothSocket = arduino.createInsecureRfcommSocketToServiceRecord(defaultUUID);
                    BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
                    bluetoothSocket.connect();
                    connectionSuccess = true;
                }

            } catch (IOException e) {
                connectionSuccess = false;
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            if (!connectionSuccess) {
                errorDialog.setMessage("Connection error!");
                errorDialog.show();

                bluetoothSocket = null;

            } else {
                Toast.makeText(getApplicationContext(), "Successfully connected", Toast.LENGTH_LONG).show();
                //isConnected = true;
            }

            progressDialog.dismiss();
        }
    }

    void initializeBT() {
        /* Check for Bluetooth support */
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

        if (bluetoothAdapter == null) {
            errorDialog.setMessage("Unfortunately, Bluetooth connection isn't supported on your device.");
            errorDialog.show();

        } else if (!bluetoothAdapter.isEnabled()) {
            /* Bluetooth disables -> enable it */
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);

        } else {
            devicesPrompt();
        }
    }

    void devicesPrompt() {
        //final ArrayList<String> devicesList = new ArrayList()<String>;
        Set<BluetoothDevice> pairedDevices;
        final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);

        pairedDevices = bluetoothAdapter.getBondedDevices();
        if (pairedDevices.size() > 0) {
            for(BluetoothDevice bluetoothDevice : pairedDevices) {
                /* Get the device's name and the address */
                //devicesList.add(bt.getName() + "\n" + bt.getAddress());
                adapter.add(bluetoothDevice.getName() + "\n" + bluetoothDevice.getAddress());
            }

        } else {
            Toast.makeText(getApplicationContext(), "No paired Bluetooth devices found!", Toast.LENGTH_LONG).show();
        }

        listDialog.setAdapter(adapter, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                //Log.d("RoverBluetooth!!", String.valueOf(which));
                //;
                String info = adapter.getItem(which);
                selectedDevice = info.substring(info.length() - 17);
                new connect().execute();
                dialog.dismiss();
            }
        });

        listDialog.show();
    }

    public void send(String message) {
        message = message + "/r";
        if (bluetoothSocket != null) {
            try {
                bluetoothSocket.getOutputStream().write(message.getBytes());
            } catch (IOException e) {
                Toast.makeText(getApplicationContext(), "Error during sending", Toast.LENGTH_SHORT).show();
                Log.d("RoverBluetooth errors", e.toString());
            }
        }
    }

    public void buttonsActions(View view) {
        int viewId = view.getId();

        if (viewId == R.id.Forwards_button) {             //ON
            send(String.valueOf(forwardsSpeed.getProgress() + 1000));

        } else if (viewId == R.id.Stop_button) {         //OFF
            send("21");

        } else if (viewId == R.id.Backwards_button) {    //Backwards
            send(String.valueOf(backwardsSpeed.getProgress() + 1500));

        } else if (viewId == R.id.Light_ON) {            //Light ON
            send("22");

        } else if (viewId == R.id.Light_OFF) {           //Light OFF
            send("23");
        }
    }
}

Answer 1

I already wrote a class to make a bluetooth connection between Android and Arduino. I suppose you're using a HC-06 (or -05 ?). My code is on github:

https://github.com/omaflak/Bluetooth-Android

I also wrote a tutorial on my blog, you may want to take a look at it:

https://causeyourestuck.io/2015/12/14/communication-between-android-and-hc-06-module/

Good luck!