Develop Reference

Perform a bluetooth scan with BluetoothAdapter in Xamarin.android

I am implementing an APP with Xamarin.
I want to perform a Bluetooth scan. And get the device found.
Here is my code.
How could I implement this to start a scan and collect the result once"Button_Scan()" is triggered?
Thank you.
[BroadcastReceiver(Enabled = true)]
public class BluetoothReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
var action = intent.Action;
if (action != BluetoothDevice.ActionFound)
{
return;
}
if (BluetoothDevice.ActionFound.Equals(action))
{
var device = (BluetoothDevice)intent.GetParcelableExtra(BluetoothDevice.ExtraDevice);
var ConnectState = device.BondState;
/*
switch (ConnectState)
{
case Bond.None:
break;
case Bond.Bonded:
break;
case Bond.Bonding:
break;
}
*/
if (device.Name != null)
{
Xamarin.Forms.Application.Current.MainPage.DisplayAlert("Found device", device.Name, "ok");
}
}
}
}
public async void Button_Scan(object sender, EventArgs e)
{
try
{
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.DefaultAdapter;
mBluetoothAdapter.Enable();
mBluetoothAdapter.StartDiscovery();
}
catch(Exception ex)
{
DisplayAlert("ex", ex.ToString(), "ok");
}
}

You have defined a BluetoothReceiver to receive the result ,you just add the device information into a deviceList.
public static List<string> mDeviceList = new List<string>();
public override void OnReceive(Context context, Intent intent)
{
string action = intent.Action;
if (BluetoothDevice.ActionFound.Equals(action))
{
BluetoothDevice device = (BluetoothDevice)intent.GetParcelableExtra(BluetoothDevice.ExtraDevice);
mDeviceList.Add(device.Name + ";" + device.Address);
}
}
Don't forget to regist the broadcast.
BluetoothReceiverreceiver = new BluetoothReceiver();
IntentFilter filter = new IntentFilter(BluetoothDevice.ActionFound);
RegisterReceiver(receiver, filter);

Unable to connect to the Bluetooth?

I am trying to connect to another Bluetooth through programmatically in android but continuously I am getting this error. anyone, please help me to connect Bluetooth. is there anything wrong with my code. i am working with bluetooth from last 2 weeks but unable to connect to the bluetooth.
is there working source code availble in github it may be helpful for me
Error-> BluetoothAdapter: getBluetoothService() called withBluetoothManagerCallback
BluetoothAdapter mBluetoothAdapter;
BluetoothDevice mBluetoothDevice;
ListView paired_lv;
Button paired_btn, listen, sendData;
TextView deviceTxt;
ClientSocket socket;
ConnectedThread connectedThread;
private static final UUID MY_UUID_SECURE =
UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
private static final UUID MY_UUID_INSECURE =
UUID.fromString("8ce255c0-200a-11e0-ac64-0800200c9a66");
private static final UUID BTMODULEUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
paired_btn = findViewById(R.id.paired_devices);
paired_lv = findViewById(R.id.paired_lv);
deviceTxt = findViewById(R.id.device_name);
listen = findViewById(R.id.listen);
sendData = findViewById(R.id.send_data);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null){
toast("Your device doesn't support bluetooth adapter");
}else if (!mBluetoothAdapter.isEnabled()){
mBluetoothAdapter.enable();
}
paired_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
pairedDevices();
}
});
paired_lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
BluetoothDevice device = (BluetoothDevice) adapterView.getItemAtPosition(i);
toast("clicket"+device.getName() );
socket = new ClientSocket(device);
socket.start();
}
});
listen.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// AcceptThread acceptThread = new AcceptThread();
//acceptThread.start();
if (socket != null){
socket.cancel();
}
}
});
sendData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String mes = "bhanu";
Log.d("BT","Send button clicked");
connectedThread.write("bhanu");
}
});
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
registerReceiver(mReceiver,filter);
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)){
Log.d("BT","device connected");
toast("device connected");
}else if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)){
toast("device disconnected");
}
}
};
public void toast(String message){
Toast.makeText(getApplicationContext(),message,Toast.LENGTH_SHORT).show();
}
public void pairedDevices(){
Set<BluetoothDevice> devices = mBluetoothAdapter.getBondedDevices();
ArrayList<BluetoothDevice> arrayList = new ArrayList<>();
if (devices.size()<0){
toast("no paired devices found");
}else {
for (BluetoothDevice device:devices){
toast(device.getName());
arrayList.add(device);
ArrayAdapter<BluetoothDevice> adapter = new ArrayAdapter<>(getApplicationContext(),android.R.layout.simple_list_item_1,arrayList);
paired_lv.setAdapter(adapter);
}
}
}
private class ClientSocket extends Thread{
private final BluetoothDevice mDevice;
private final BluetoothSocket mSocket;
public ClientSocket(BluetoothDevice device,Boolean isSecure) {
mDevice = device;
BluetoothSocket tmp = null;
boolean secure = isSecure;
try {
tmp = device.createInsecureRfcommSocketToServiceRecord(MY_UUID_INSECURE);
} catch (IOException e) {
e.printStackTrace();
}
mSocket = tmp;
}
#Override
public void run() {
mBluetoothAdapter.cancelDiscovery();
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDED){
Log.d("BT","bonded");
}
if (BluetoothDevice.DEVICE_TYPE_LE == mDevice.getType()){
try {
Log.d("BT","Connecting BT");
Log.d("BT","socket info"+ mSocket);
mSocket.connect();
Log.d("BT","Connected BT");
} catch (IOException e) {
cancel();
e.printStackTrace();
}
}
if (mSocket != null){
connectedThread = new ConnectedThread(mSocket);
}
}
public void cancel(){
if (mSocket.isConnected()){
try {
mSocket.close();
Log.d("BT","socket was closed");
} catch (IOException e) {
e.printStackTrace();
}
}else {
Log.d("BT","device not connected to the any other device");
}
}
}
private class AcceptThread extends Thread{
private final BluetoothServerSocket mServerSocket;
public AcceptThread() {
BluetoothServerSocket tmp = null;
try {
tmp = mBluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord("Bhanu",MY_UUID_INSECURE);
} catch (IOException e) {
e.printStackTrace();
}
mServerSocket = tmp;
}
#Override
public void run() {
BluetoothSocket socket = null;
while (true){
try {
//Toast.makeText(getApplicationContext(),"ready to accept",Toast.LENGTH_SHORT).show();
Log.d("BT","ready to accept socket");
socket = mServerSocket.accept();
Log.d("BT","socket accepted");
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
#Override
protected void onDestroy() {
unregisterReceiver(mReceiver);
super.onDestroy();
}
}

You need a BluetoothManager
BluetoothManager mBluetoothManager;
if (mBluetoothManager == null) {
mBluetoothManager = (BluetoothManager) getSystemService(this);
if (mBluetoothManager == null) {
Log.e(TAG, "Unable to initialize BluetoothManager.");
}
}
mBluetoothAdapter = mBluetoothManager.getAdapter();
if (mBluetoothAdapter == null) {
Log.e(TAG, "Unable to obtain a BluetoothAdapter.");
}

Bluetooth Connection

I've looked at quite a lot of topics on this in different forums and none seem to help me.
I recently bought an Elegoo car kit, which is compatible with the Arduino IDE, and it comes with different types of code and what not. they even have their own Android app.
My problem is I want to create my own android Bluetooth application that connects/pairs with the module and can control the car remotely. I have my application up and running, it can scan for nearby devices and the HC-08 module appears in the list but I am not able to connect. when I try to connect it says it can't communicate with HC-08. I am pretty sure the problem lies in the android end as the elegoo Bluetooth app connects no problem at all with the Bluetooth module if there is any code on the elegoo board or not. The bluetooth module is a HC-08.
Can someone help me with this ?
Also I am following this youtube tutorial so the credit goes to him for the code.
https://www.youtube.com/watch?v=YJ0JQXcNNTA
Here is the main activity code:
public class MainActivity extends AppCompatActivity implements
AdapterView.OnItemClickListener{
private static final String TAG = "MainActivity";
BluetoothAdapter mBluetoothAdapter;
Button btnEnableDisable_Discoverable;
public ArrayList<BluetoothDevice> mBTDevices = new ArrayList<>();
public DeviceListAdapter mDeviceListAdapter;
ListView lvNewDevices;
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (action.equals(mBluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, mBluetoothAdapter.ERROR);
switch(state){
case BluetoothAdapter.STATE_OFF:
Log.d(TAG, "onReceive: STATE OFF");
break;
case BluetoothAdapter.STATE_TURNING_OFF:
Log.d(TAG, "mBroadcastReceiver1: STATE TURNING OFF");
break;
case BluetoothAdapter.STATE_ON:
Log.d(TAG, "mBroadcastReceiver1: STATE ON");
break;
case BluetoothAdapter.STATE_TURNING_ON:
Log.d(TAG, "mBroadcastReceiver1: STATE TURNING ON");
break;
}
}
}
};
/**
* Broadcast Receiver for changes made to bluetooth states such as:
* 1) Discoverability mode on/off or expire.
*/
private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {
int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE, BluetoothAdapter.ERROR);
switch (mode) {
//Device is in Discoverable Mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Enabled.");
break;
//Device not in discoverable mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Disabled. Able to receive connections.");
break;
case BluetoothAdapter.SCAN_MODE_NONE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Disabled. Not able to receive connections.");
break;
case BluetoothAdapter.STATE_CONNECTING:
Log.d(TAG, "mBroadcastReceiver2: Connecting....");
break;
case BluetoothAdapter.STATE_CONNECTED:
Log.d(TAG, "mBroadcastReceiver2: Connected.");
break;
}
}
}
};
/**
* Broadcast Receiver for listing devices that are not yet paired
* -Executed by btnDiscover() method.
*/
private BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
Log.d(TAG, "onReceive: ACTION FOUND.");
if (action.equals(BluetoothDevice.ACTION_FOUND)){
BluetoothDevice device = intent.getParcelableExtra (BluetoothDevice.EXTRA_DEVICE);
mBTDevices.add(device);
Log.d(TAG, "onReceive: " + device.getName() + ": " + device.getAddress());
mDeviceListAdapter = new DeviceListAdapter(context, R.layout.device_adapter_view, mBTDevices);
lvNewDevices.setAdapter(mDeviceListAdapter);
}
}
};
/**
* Broadcast Receiver that detects bond state changes (Pairing status changes)
*/
private final BroadcastReceiver mBroadcastReceiver4 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED)){
BluetoothDevice mDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//3 cases:
//case1: bonded already
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDED){
Log.d(TAG, "BroadcastReceiver: BOND_BONDED.");
}
//case2: creating a bone
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDING) {
Log.d(TAG, "BroadcastReceiver: BOND_BONDING.");
}
//case3: breaking a bond
if (mDevice.getBondState() == BluetoothDevice.BOND_NONE) {
Log.d(TAG, "BroadcastReceiver: BOND_NONE.");
}
}
}
};
#Override
protected void onDestroy() {
Log.d(TAG, "onDestroy: called.");
super.onDestroy();
unregisterReceiver(mBroadcastReceiver1);
unregisterReceiver(mBroadcastReceiver2);
unregisterReceiver(mBroadcastReceiver3);
unregisterReceiver(mBroadcastReceiver4);
//mBluetoothAdapter.cancelDiscovery();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnONOFF = (Button) findViewById(R.id.btnONOFF);
btnEnableDisable_Discoverable = (Button) findViewById(R.id.btnDiscoverable_on_off);
lvNewDevices = (ListView) findViewById(R.id.lvNewDevices);
mBTDevices = new ArrayList<>();
//Broadcasts when bond state changes (ie:pairing)
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
registerReceiver(mBroadcastReceiver4, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
lvNewDevices.setOnItemClickListener(MainActivity.this);
btnONOFF.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.d(TAG, "onClick: enabling/disabling bluetooth.");
enableDisableBT();
}
});
}
public void enableDisableBT(){
if(mBluetoothAdapter == null){
Log.d(TAG, "enableDisableBT: Does not have BT capabilities.");
}
if(!mBluetoothAdapter.isEnabled()){
Log.d(TAG, "enableDisableBT: enabling BT.");
Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBTIntent);
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
if(mBluetoothAdapter.isEnabled()){
Log.d(TAG, "enableDisableBT: disabling BT.");
mBluetoothAdapter.disable();
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
}
public void btnEnableDisable_Discoverable(View view) {
Log.d(TAG, "btnEnableDisable_Discoverable: Making device discoverable for 300 seconds.");
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
IntentFilter intentFilter = new IntentFilter(mBluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
registerReceiver(mBroadcastReceiver2,intentFilter);
}
public void btnDiscover(View view) {
Log.d(TAG, "btnDiscover: Looking for unpaired devices.");
if(mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.cancelDiscovery();
Log.d(TAG, "btnDiscover: Canceling discovery.");
//check BT permissions in manifest
checkBTPermissions();
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
if(!mBluetoothAdapter.isDiscovering()){
//check BT permissions in manifest
checkBTPermissions();
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
}
/**
* This method is required for all devices running API23+
* Android must programmatically check the permissions for bluetooth. Putting the proper permissions
* in the manifest is not enough.
*
* NOTE: This will only execute on versions > LOLLIPOP because it is not needed otherwise.
*/
private void checkBTPermissions() {
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP){
int permissionCheck = this.checkSelfPermission("Manifest.permission.ACCESS_FINE_LOCATION");
permissionCheck += this.checkSelfPermission("Manifest.permission.ACCESS_COARSE_LOCATION");
if (permissionCheck != 0) {
this.requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 1001); //Any number
}
}else{
Log.d(TAG, "checkBTPermissions: No need to check permissions. SDK version < LOLLIPOP.");
}
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
//first cancel discovery because its very memory intensive.
mBluetoothAdapter.cancelDiscovery();
Log.d(TAG, "onItemClick: You Clicked on a device.");
String deviceName = mBTDevices.get(i).getName();
String deviceAddress = mBTDevices.get(i).getAddress();
Log.d(TAG, "onItemClick: deviceName = " + deviceName);
Log.d(TAG, "onItemClick: deviceAddress = " + deviceAddress);
//create the bond.
//NOTE: Requires API 17+? I think this is JellyBean
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2){
Log.d(TAG, "Trying to pair with " + deviceName);
mBTDevices.get(i).createBond();
}
}
}
/// Here is also my DeviceListAdapter code:
public class DeviceListAdapter extends ArrayAdapter<BluetoothDevice> {
private LayoutInflater mLayoutInflater;
private ArrayList<BluetoothDevice> mDevices;
private int mViewResourceId;
public DeviceListAdapter(Context context, int tvResourceId, ArrayList<BluetoothDevice> devices){
super(context, tvResourceId,devices);
this.mDevices = devices;
mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mViewResourceId = tvResourceId;
}
public View getView(int position, View convertView, ViewGroup parent) {
convertView = mLayoutInflater.inflate(mViewResourceId, null);
BluetoothDevice device = mDevices.get(position);
if (device != null) {
TextView deviceName = (TextView) convertView.findViewById(R.id.tvDeviceName);
TextView deviceAdress = (TextView) convertView.findViewById(R.id.tvDeviceAddress);
if (deviceName != null) {
deviceName.setText(device.getName());
}
if (deviceAdress != null) {
deviceAdress.setText(device.getAddress());
}
}
return convertView;
}
}

Some of the tutorials on Bluetooth are pretty old! I just got Arduino-Android Bluetooth communication working last week so this should work for you! First in your manifest file add these permissions:
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
Then use this in your main.
public class MainActivity extends AppCompatActivity {
private final String DEVICE_ADDRESS="benamekhoda"; //I actually used Device Name instead of address
private final UUID PORT_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb"); //Serial Port Service UUID
private BluetoothDevice device; //Our Bluetooth Device
private BluetoothSocket socket;
private OutputStream outputStream;
private InputStream inputStream;
Button startButton, sendButton,clearButton,stopButton;
TextView textView;
EditText editText;
boolean deviceConnected=false;
Thread thread;
byte buffer[];
int bufferPosition;
boolean stopThread;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.edittext);
textView = (TextView) findViewById(R.id.textview);
startButton = (Button) findViewById(R.id.buttonStart);
startButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(BTinit())
{
if(BTconnect())
{
setUiEnabled(true);
deviceConnected=true;
beginListenForData();
textView.append("\nConnection Opened!\n");
}
else{
Toast.makeText(getApplicationContext(),"BTconnect false",Toast.LENGTH_SHORT).show();
}
}
else{
Toast.makeText(getApplicationContext(),"BTinit false",Toast.LENGTH_SHORT).show();
}
}
});
sendButton = (Button) findViewById(R.id.buttonSend);
sendButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String string = editText.getText().toString();
string.concat("\n");
try {
outputStream.write(string.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
textView.append("\nSent Data:"+string+"\n");
}
});
clearButton = (Button) findViewById(R.id.buttonClear);
clearButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
onClickClear(view);
}
});
stopButton = (Button) findViewById(R.id.buttonStop);
stopButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
onClickSend(view);
}
});
setUiEnabled(false);
}
public void setUiEnabled(boolean bool)
{
startButton.setEnabled(!bool);
sendButton.setEnabled(bool);
stopButton.setEnabled(bool);
textView.setEnabled(bool);
}
public boolean BTinit()
{
boolean found=false;
BluetoothAdapter bluetoothAdapter=BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null) {
Toast.makeText(getApplicationContext(),"Device doesnt Support Bluetooth",Toast.LENGTH_SHORT).show();
}
if(!bluetoothAdapter.isEnabled())
{
Intent enableAdapter = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableAdapter, 0);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
Set<BluetoothDevice> bondedDevices = bluetoothAdapter.getBondedDevices(); //Something like ArrayList but no duplicate is allowed and data is unordered
if(bondedDevices.isEmpty())
{
Toast.makeText(getApplicationContext(),"Please Pair the Device first",Toast.LENGTH_SHORT).show();
}
else
{
for (BluetoothDevice iterator : bondedDevices)
{
if(iterator.getName().equals(DEVICE_ADDRESS))
{
device=iterator;
Toast.makeText(getApplicationContext(),"found the device",Toast.LENGTH_SHORT).show();
found=true;
break;
}
}
}
return found;
}
public boolean BTconnect()
{
boolean connected=true;
try {
socket = device.createRfcommSocketToServiceRecord(PORT_UUID);
socket.connect();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),"throw1",Toast.LENGTH_SHORT).show();
connected=false;
}
if(connected)
{
try {
outputStream=socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),"throw2",Toast.LENGTH_SHORT).show();
}
try {
inputStream=socket.getInputStream();
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),"throw3",Toast.LENGTH_SHORT).show();
}
}
return connected;
}
void beginListenForData()
{
final Handler handler = new Handler();
stopThread = false;
buffer = new byte[1024];
Thread thread = new Thread(new Runnable()
{
public void run()
{
while(!Thread.currentThread().isInterrupted() && !stopThread)
{
try
{
int byteCount = inputStream.available();
if(byteCount > 0)
{
byte[] rawBytes = new byte[byteCount];
inputStream.read(rawBytes);
final String string=new String(rawBytes,"UTF-8");
handler.post(new Runnable() {
public void run()
{
textView.append(string);
}
});
}
}
catch (IOException ex)
{
stopThread = true;
Toast.makeText(getApplicationContext(),"throw4",Toast.LENGTH_SHORT).show();
}
}
}
});
thread.start();
}
public void onClickSend(View view) {
String string = editText.getText().toString();
string.concat("\n");
try {
outputStream.write(string.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
textView.append("\nSent Data:"+string+"\n");
}
public void onClickStop(View view) throws IOException {
stopThread = true;
outputStream.close();
inputStream.close();
socket.close();
setUiEnabled(false);
deviceConnected=false;
textView.append("\nConnection Closed!\n");
}
public void onClickClear(View view) {
textView.setText("");
}
}
I got it from this awesome tutorial by Hariharan Mathavan from All About Circuits.

NullPointerException in `BluetoothAdapter` when startService() is invoked [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
Error I'm getting null point exception in Bluetooth when I'm starting a service.
LiveFragment.class
public class LiveFragment extends Fragment {
// Intent request codes
private static final int REQUEST_CONNECT_DEVICE_SECURE = 1;
private static final int REQUEST_CONNECT_DEVICE_INSECURE = 2;
private static final int REQUEST_ENABLE_BT = 3;
private BluetoothAdapter mBluetoothAdapter =null;
public BluetoothChatService mChatService = null;
private PowerManager.WakeLock wakeLock = null;
private PowerManager powerManager = null;
private String mConnectedDeviceName = null;
private boolean isServiceBound;
private boolean preRequisites = true;
private SharedPreferences prefs;
private BroadcastReceiver broadcastReceiver;
private Context c;
private AbstractGatewayService ab;
protected ImageView blue_onoffBut, gps_Button, obd_inidca, ss_button, bluetooth_indicator, gps_indicator,obd_connectButt;
protected TextView ss_Status,btStatusTextView,obdStatusTextView,gpsStatusTextView;
private LinearLayout vv;
protected BluetoothSocket sock = null;
public LiveFragment() {
// Required empty public constructor
}
private final Runnable mQueueCommands = new Runnable() {
public void run() {
Log.d(TAG, "Runnable mQueueCommands ()");
if (ab != null && ab.isRunning() && ab.queueEmpty()) {
queueCommands();
}
// run again in period defined in preferences
new Handler().postDelayed(mQueueCommands, 4000);
}
};
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
final View view = inflater.inflate(R.layout.fragment_live, container, false);
blue_onoffBut = (ImageView) view.findViewById(R.id.blutooth_butoon);
gps_Button = (ImageView) view.findViewById(R.id.gps_button);
obd_inidca = (ImageView) view.findViewById(R.id.obd_Indicator);
ss_button = (ImageView) view.findViewById(ssButton);
gps_indicator = (ImageView) view.findViewById(R.id.gps_indicator);
bluetooth_indicator = (ImageView) view.findViewById(R.id.bluetooth_indicator);
obd_connectButt = (ImageView) view.findViewById(R.id.Obd_Connect_Button);
ss_Status = (TextView) view.findViewById(R.id.statusTx);
btStatusTextView = (TextView) view.findViewById(R.id.blue);
obdStatusTextView = (TextView) view.findViewById(R.id.obd);
gpsStatusTextView = (TextView) view.findViewById(R.id.gps);
vv = (LinearLayout) view.findViewById(R.id.fragment_live_layout);
ss_Status.setTextColor(getResources().getColor(R.color.colorGreen));
if (mBluetoothAdapter.isEnabled()) {
bluetooth_indicator.setImageResource(R.drawable.green_circle);
} else {
bluetooth_indicator.setImageResource(R.drawable.red_circle);
}
gps_Button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final LocationManager manager = (LocationManager) getActivity().getSystemService( Context.LOCATION_SERVICE );
if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
buildAlertMessageNoGps();
}
else {
showToast("Already GPS is ON");
}
}
});
blue_onoffBut.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (!mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.enable();
showToast("Bluetooth Turned ON"+"\n"+"Connect Your OBD now");
bluetooth_indicator.setImageResource(R.drawable.green_circle);
mChatService = new BluetoothChatService(getActivity(), mHandler);
if (mChatService != null) {
// Only if the state is STATE_NONE, do we know that we haven't started already
if (mChatService.getState() == BluetoothChatService.STATE_NONE) {
// Start the Bluetooth chat services
mChatService.start();
}
}
} else if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
mBluetoothAdapter.cancelDiscovery();
obd_inidca.setImageResource(R.drawable.red_circle);
showToast("Bluetooth Turned OFF");
bluetooth_indicator.setImageResource(R.drawable.red_circle);
}
}
});
ss_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mBluetoothAdapter.isEnabled() && mChatService.getState() == BluetoothChatService.STATE_CONNECTED) {
startLiveData();
} else if (!mBluetoothAdapter.isEnabled()) {
showToast("Turn ON Bluetooth to Continue");
}
else if (!(mChatService.getState() == BluetoothChatService.STATE_CONNECTED)){
showToast("Select your OBD to Start ");
}
}
});
obd_connectButt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(mBluetoothAdapter.isEnabled()) {
Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class);
startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_SECURE);
}
else if (!mBluetoothAdapter.isEnabled()){
showToast("Turn ON Bluetooth to Connect OBD");
}
}
});
return view;
}
private ServiceConnection serviceConn = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName className, IBinder binder) {
Log.d(TAG, className.toString() + " service is bound");
isServiceBound = true;
ab = ((AbstractGatewayService.AbstractGatewayServiceBinder) binder).getService();
ab.setContext(getActivity());
Log.d(TAG, "Starting live data");
try {
ab.startService();
if (preRequisites)
btStatusTextView.setText("Connected");
} catch (IOException ioe) {
Log.e(TAG, "Failure Starting live data");
btStatusTextView.setText("Connection failed");
doUnbindService();
}
}
#Override
protected Object clone() throws CloneNotSupportedException {
Log.d(TAG, "CloneNotSupportedException ");
return super.clone();
}
#Override
public void onServiceDisconnected(ComponentName className) {
Log.d(TAG, className.toString() + " service is unbound");
isServiceBound = false;
}
};
public static String LookUpCommand(String txt) {
Log.d(TAG, "LookUpCommand() ");
for (AvailableCommandNames item : AvailableCommandNames.values()) {
if (item.getValue().equals(txt)) return item.name();
}
return txt;
}
public void updateTextView(final TextView view, final String txt) {
Log.d(TAG, "updateTextView() ");
new Handler().post(new Runnable() {
public void run() {
view.setText(txt);
}
});
}
#Subscribe(threadMode = ThreadMode.MAIN)
public void stateUpdate(ObdCommandJob job) {
final String cmdName = job.getCommand().getName();
String cmdResult = "";
final String cmdID = LookUpCommand(cmdName);
Log.d(TAG, "stateUpdate() ");
if (job.getState().equals(ObdCommandJob.ObdCommandJobState.EXECUTION_ERROR)) {
cmdResult = job.getCommand().getResult();
if (cmdResult != null && isServiceBound) {
obdStatusTextView.setText(cmdResult.toLowerCase());
}
} else if (job.getState().equals(ObdCommandJob.ObdCommandJobState.BROKEN_PIPE)) {
if (isServiceBound)
stopLiveData();
} else if (job.getState().equals(ObdCommandJob.ObdCommandJobState.NOT_SUPPORTED)) {
cmdResult = "NA";
} else {
cmdResult = job.getCommand().getFormattedResult();
if (isServiceBound)
obdStatusTextView.setText("Receiving data...");
}
cmdResult.replace("NODATA", "0");
if (vv.findViewWithTag(cmdID) != null) {
TextView existingTV = (TextView) vv.findViewWithTag(cmdID);
existingTV.setText(cmdResult);
}
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
// Get local Bluetooth adapter
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
// If the adapter is null, then Bluetooth is not supported
if (mBluetoothAdapter == null) {
FragmentActivity activity = getActivity();
Toast.makeText(activity, "No Bluetooth Feature in Device", Toast.LENGTH_LONG).show();
activity.finish();
}
}
#Override
public void onStart() {
super.onStart();
final LocationManager manager = (LocationManager) getActivity().getSystemService( Context.LOCATION_SERVICE );
if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
gps_indicator.setImageResource(R.drawable.red_circle);
}
if(mBluetoothAdapter.isEnabled()){
mBluetoothAdapter.disable();
bluetooth_indicator.setImageResource(R.drawable.red_circle);
}
}
#Override
public void onResume() {
super.onResume();
powerManager = (PowerManager) getActivity().getSystemService(Context.POWER_SERVICE);
wakeLock = powerManager.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "ObdReader");
final LocationManager manager = (LocationManager) getActivity().getSystemService( Context.LOCATION_SERVICE );
if ( manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
gps_indicator.setImageResource(R.drawable.green_circle);
} else {
gps_indicator.setImageResource(R.drawable.red_circle);
}
EventBus.getDefault().register(this);
if(mBluetoothAdapter.isEnabled()) {
if (mChatService != null) {
// Only if the state is STATE_NONE, do we know that we haven't started already
if (mChatService.getState() == BluetoothChatService.STATE_NONE) {
// Start the Bluetooth chat services
mChatService.start();
}
}
}
}
#Override
public void onPause() {
super.onPause();
Log.d(TAG, "Pausing..");
releaseWakeLockIfHeld();
EventBus.getDefault().unregister(this);
}
private void showToast(String message) {
final Toast toast = Toast.makeText(getContext(), message, Toast.LENGTH_SHORT);
toast.show();
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
toast.cancel();
}
}, 500);
}
#Override
public void onDestroy() {
/* unregisterReceiver(mReceiver);*/
super.onDestroy();
releaseWakeLockIfHeld();
if (mChatService != null) {
mChatService.stop();
}
if (isServiceBound) {
doUnbindService();
}
if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
}
showToast("Take Care!");
}
private void startLiveData() {
if (mChatService.getState() == BluetoothChatService.STATE_CONNECTED) {
Log.d(TAG, "Starting live data..");
ss_Status.setText("Stop");
ss_Status.setTextColor(getResources().getColor(R.color.colorRed));
wakeLock.acquire();
ss_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ss_Status.setText("Go Live");
ss_Status.setTextColor(getResources().getColor(R.color.colorGreen));
stopLiveData();
}
});
doBindService();
LocalBroadcastManager.getInstance(getActivity()).registerReceiver((broadcastReceiver), new IntentFilter(OBD_GATEWAY_SERVICE));
new Handler().post(mQueueCommands);
}
}
private void stopLiveData() {
Log.d(TAG, "Stopping live data..");
releaseWakeLockIfHeld();
new Handler().removeCallbacks(mQueueCommands);
ss_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ss_Status.setText("Go Live");
ss_Status.setTextColor(getResources().getColor(R.color.colorGreen));
startLiveData();
}
});
doUnbindService();
LocalBroadcastManager.getInstance(getActivity()).unregisterReceiver(broadcastReceiver);
}
private void queueCommands() {
Log.d(TAG, "LiveFragment queueCommands() ");
if (isServiceBound) {
for (ObdCommand Command : ObdConfig.getCommands()) {
if (prefs.getBoolean(Command.getName(), true))
ab.queueJob(new ObdCommandJob(Command));
}
}
}
private void doBindService() {
if (!isServiceBound) {
Log.d(TAG, "Binding OBD service..");
if (preRequisites) {
btStatusTextView.setText("Connecting.....");
Intent serviceIntent = new Intent(getActivity(),ObdGatewayService.class);
getActivity().bindService(serviceIntent, serviceConn, Context.BIND_AUTO_CREATE);
}
}
}
private void doUnbindService() {
if (isServiceBound) {
if (ab.isRunning()) {
ab.stopService();
if (preRequisites)
btStatusTextView.setText("Ready...");
}
Log.d(TAG, "Unbinding OBD service..");
getActivity().unbindService(serviceConn);
isServiceBound = false;
obdStatusTextView.setText("Disconnected");
}
}
private final Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
FragmentActivity activity = getActivity();
switch (msg.what) {
case Constants.MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BluetoothChatService.STATE_CONNECTED:
obd_inidca.setImageResource(R.drawable.green_circle);
break;
case BluetoothChatService.STATE_CONNECTING:
obd_inidca.setImageResource(R.drawable.orange_circle);
break;
case BluetoothChatService.STATE_LISTEN:
case BluetoothChatService.STATE_NONE:
obd_inidca.setImageResource(R.drawable.red_circle);
break;
}
break;
case Constants.MESSAGE_DEVICE_NAME:
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(Constants.DEVICE_NAME);
if (null != activity) {
Toast.makeText(activity, "Connected to "
+ mConnectedDeviceName, Toast.LENGTH_SHORT).show();
obd_inidca.setImageResource(R.drawable.green_circle);
}
break;
case Constants.MESSAGE_TOAST:
if (null != activity) {
Toast.makeText(activity, msg.getData().getString(Constants.TOAST),
Toast.LENGTH_SHORT).show();
}
break;
}
}
};
public void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case REQUEST_CONNECT_DEVICE_SECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
try {
connectDevice(data, true);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
private void connectDevice(Intent data, boolean secure) throws IOException {
// Get the device MAC address
String address = data.getExtras()
.getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
// Get the BluetoothDevice object
BluetoothDevice dev = mBluetoothAdapter.getRemoteDevice(address);
// Attempt to connect to the device
mChatService.connect(dev, secure);
}.
This is ObdGateway service class:
public class ObdGatewayService extends AbstractGatewayService {
private static final String TAG = ObdGatewayService.class.getName();
#Inject
SharedPreferences prefs;
private BluetoothDevice dev = null;
private BluetoothSocket sock = null;
private BluetoothChatService mChatservice = null;
private BluetoothAdapter bluetoothAdapter =null;
public final static String JOB_NAME_STAMP = "Name";
public final static String JOB_STATE_STAMP = "State";
public final static String JOB_RESULT_STAMP = "Result";
public final static String JOB_FORMATED_RESULT_STAMP = "Formated REsult";
public final static String OBD_GATEWAY_SERVICE = "com.samplersoft.saz.Obd.ObdGatewayService";
public void startService() throws IOException {
Log.d(TAG, "Starting service..");
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
// get the remote Bluetooth device
if(mChatservice.getState() != BluetoothChatService.STATE_CONNECTED){
Toast.makeText(ctx, "No Bluetooth device selected", Toast.LENGTH_LONG).show();
// log error
Log.e(TAG, "No Bluetooth device has been selected.");
stopService();
throw new IOException();
}
else
{
Log.d(TAG, "Stopping Bluetooth discovery.");
bluetoothAdapter.cancelDiscovery();
try {
startObdConnection();
} catch (Exception e) {
Log.e(
TAG,
"There was an error while establishing connection. -> "
+ e.getMessage()
);
// in case of failure, stop this service.
stopService();
throw new IOException();
}
}
}
private void startObdConnection() throws IOException {
Log.d(TAG, "Starting OBD connection..");
isRunning = true;
if(mChatservice.getState() == BluetoothChatService.STATE_CONNECTED){
// Let's configure the connection.
Log.d(TAG, "Queueing jobs for connection configuration..");
queueJob(new ObdCommandJob(new ObdResetCommand()));
try { Thread.sleep(500); } catch (InterruptedException e) { e.printStackTrace(); }
queueJob(new ObdCommandJob(new EchoOffCommand()));
queueJob(new ObdCommandJob(new EchoOffCommand()));
queueJob(new ObdCommandJob(new LineFeedOffCommand()));
queueJob(new ObdCommandJob(new TimeoutCommand(62)));
// Get protocol from preferences
queueJob(new ObdCommandJob(new SelectProtocolCommand(ObdProtocols.valueOf("AUTO"))));
// Job for returning dummy data
queueJob(new ObdCommandJob(new AmbientAirTemperatureCommand()));
queueCounter = 0L;
Log.d(TAG, "Initialization jobs queued.");
}
else {
stopService();
throw new IOException();
}
}
#Override
public void queueJob(ObdCommandJob job) {
// This is a good place to enforce the imperial units option
//job.getCommand().useImperialUnits(prefs.getBoolean(ConfigActivity.IMPERIAL_UNITS_KEY, false));
// Now we can pass it along
super.queueJob(job);
}
protected void executeQueue() throws InterruptedException {
Log.d(TAG, "Executing queue..");
while (!Thread.currentThread().isInterrupted()) {
ObdCommandJob job = null;
try {
job = jobsQueue.take();
// log job
Log.d(TAG, "Taking job[" + job.getId() + "] from queue..");
if (job.getState().equals(ObdCommandJob.ObdCommandJobState.NEW)) {
Log.d(TAG, "Job state is NEW. Run it..");
job.setState(ObdCommandJob.ObdCommandJobState.RUNNING);
if (sock.isConnected()) {
job.getCommand().run(sock.getInputStream(), sock.getOutputStream());
} else {
job.setState(ObdCommandJob.ObdCommandJobState.EXECUTION_ERROR);
Log.e(TAG, "Can't run command on a closed socket.");
}
} else
// log not new job
Log.e(TAG,
"Job state was not new, so it shouldn't be in queue. BUG ALERT!");
} catch (InterruptedException i) {
Thread.currentThread().interrupt();
} catch (UnsupportedCommandException u) {
if (job != null) {
job.setState(ObdCommandJob.ObdCommandJobState.NOT_SUPPORTED);
}
Log.d(TAG, "Command not supported. -> " + u.getMessage());
} catch (IOException io) {
if (job != null) {
if(io.getMessage().contains("Broken pipe"))
job.setState(ObdCommandJob.ObdCommandJobState.BROKEN_PIPE);
else
job.setState(ObdCommandJob.ObdCommandJobState.EXECUTION_ERROR);
}
Log.e(TAG, "IO error. -> " + io.getMessage());
} catch (Exception e) {
if (job != null) {
job.setState(ObdCommandJob.ObdCommandJobState.EXECUTION_ERROR);
}
Log.e(TAG, "Failed to run command. -> " + e.getMessage());
}
ObdCommandJob job2 = job;
if(job2 !=null)
EventBus.getDefault().post(job2);
}
}
public void stopService() {
Log.d(TAG, "Stopping service..");
jobsQueue.clear();
isRunning = false;
if (sock != null)
// close socket
try {
sock.close();
} catch (IOException e) {
Log.e(TAG, e.getMessage());
}
// kill service
stopSelf();
}
public boolean isRunning() {
return isRunning;
}
}.
This is Abstract Class where service method gets called from from Livefragment Class from serivceConnection().
public abstract class AbstractGatewayService extends RoboService {
private static final String TAG = AbstractGatewayService.class.getName();
private final IBinder binder = new AbstractGatewayServiceBinder();
protected Context ctx;
protected boolean isRunning = false;
protected Long queueCounter = 0L;
protected BlockingQueue<ObdCommandJob> jobsQueue = new LinkedBlockingQueue<>();
Thread t = new Thread(new Runnable() {
#Override
public void run() {
try {
executeQueue();
} catch (InterruptedException e) {
t.interrupt();
}
}
});
protected LocalBroadcastManager broadcastManager;
#Override
public IBinder onBind(Intent intent) {
return binder;
}
#Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "Creating service..");
final BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
t.start();
Log.d(TAG, "Service created.");
}
#Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "Destroying service...");
t.interrupt();
broadcastManager = LocalBroadcastManager.getInstance(this);
Log.d(TAG, "Service destroyed.");
}
public boolean isRunning() {
return isRunning;
}
public boolean queueEmpty() {
return jobsQueue.isEmpty();
}
public void queueJob(ObdCommandJob job) {
queueCounter++;
Log.d(TAG, "Adding job[" + queueCounter + "] to queue..");
job.setId(queueCounter);
try {
jobsQueue.put(job);
Log.d(TAG, "Job queued successfully.");
} catch (InterruptedException e) {
job.setState(ObdCommandJob.ObdCommandJobState.QUEUE_ERROR);
Log.e(TAG, "Failed to queue job.");
}
}
public void setContext(Context c) {
ctx = c;
}
abstract protected void executeQueue() throws InterruptedException;
abstract public void startService() throws IOException;
abstract public void stopService();
public class AbstractGatewayServiceBinder extends Binder {
public AbstractGatewayService getService() {
return AbstractGatewayService.this;
}
}
}.

You are getting the exception because in class ObdGatewayService your class member mChatservice is not the same as mChatservice in class LiveFragment
They are just different member variables
mChatservice gets assigned like this in your Fragment
mChatService = new BluetoothChatService(getActivity(), mHandler);
You need to pass this reference to ObdGatewayService 's startService() like this where ever you are instantiating/invoking it:-
ObdGatewayService ogs;
....
ogs.startservice(mChatservice); // This is fragment's member reference
And in ObdGatewayService you have to assign it accordingly:-
public void startService(BluetoothChatService _mChatservice) throws IOException {
Log.d(TAG, "Starting service..");
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
mChatservice = _mChatservice //Assignment YOU ARE MISSING THIS
.......
.......
}

How to connect to a paired bluetooth device?

My code can scan and pair bluetooth speakers. However, in order to stream audio to the paired device, I have to pair via device settings or it won't work. How do I do this via my app?
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("Connecting..");
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("Connected! now you can stream");
} else if (state == BluetoothDevice.BOND_NONE && prevState == BluetoothDevice.BOND_BONDED){
showToast("Disconnected");
}
mAdapter.notifyDataSetChanged();
}
}
};
}