Develop Reference

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.

App crashed due to looper.prepare() in the beginlistendata() function

public class BluetoothActivity extends Activity {
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// Whenever a remote Bluetooth device is found
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// Add the name and address to an array adapter to show in a ListView
adapter.add(bluetoothDevice.getName() + "\n"
+ bluetoothDevice.getAddress());
}
}
};
//declaration
TextView myLabel;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
volatile boolean stopWorker;
private BluetoothAdapter mBluetoothAdapter;
private ListView listview;
private ArrayAdapter adapter;
private ToggleButton toggleButton;
private static final int REQUEST_ENABLE_BT =0;
private static final int DISCOVERABLE_DURATION = 0;
private static final int DISCOVERABLE_BT_REQUEST_CODE = 2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.bluetooth_main);
toggleButton = (ToggleButton) findViewById(R.id.toggleButton);
listview = (ListView) findViewById(R.id.listView);
// ListView Item Click Listener
listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// ListView Clicked item value
String itemValue = (String) listview.getItemAtPosition(position);
Toast.makeText(getApplicationContext(), "clicked", Toast.LENGTH_LONG).show();
String MAC = itemValue.substring(itemValue.length() - 17);
BluetoothDevice bluetoothDevice = mBluetoothAdapter.getRemoteDevice(MAC);
// Initiate a connection request in a separate thread
ConnectingThread t = new ConnectingThread(bluetoothDevice);
t.start();
}
});
adapter = new ArrayAdapter
(this,android.R.layout.simple_list_item_1);
listview.setAdapter(adapter);
//verify bluetooth is supported on the device
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
// Device does not support Bluetooth
if (mBluetoothAdapter == null) {
}
}//end oncreate
public void onToggle(View view) {
adapter.clear();
if (toggleButton.isChecked()){
//enable bluetooth
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
Toast.makeText(getApplicationContext(), "Turned on", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(getApplicationContext(),"Already on", Toast.LENGTH_LONG).show();
//To discover remote Bluetooth devices
discoverDevices();
// Make local device discoverable by other devices
makeDiscoverable();
}
}//end of 1st if
else{
//turn off bluetooth
mBluetoothAdapter.disable();
adapter.clear();
Toast.makeText(getApplicationContext(),"Turned off" ,Toast.LENGTH_LONG).show();
}
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_ENABLE_BT) {
// Bluetooth successfully enabled!
if (resultCode == Activity.RESULT_OK) {
Toast.makeText(getApplicationContext(), "Bluetooth is now enabled.",Toast.LENGTH_SHORT).show();
// Make local device discoverable by other devices
makeDiscoverable();
// To discover remote Bluetooth devices
Log.e("calldiscover", "func");
discoverDevices();
Log.e("Discover", "device");
// Start a thread to create a server socket to listen
// for connection request
Log.e("listenthread", "listenthread");
ListeningThread t = new ListeningThread();
Log.e("call", "t.start");
t.start();
Log.e("t.start", "over");
}
else {
// RESULT_CANCELED as user refused
Toast.makeText(getApplicationContext(), "Bluetooth is not enabled.",
Toast.LENGTH_SHORT).show();
// Turn off togglebutton
toggleButton.setChecked(false);
}
}//end of 1st if
}
protected void discoverDevices(){
// To scan for remote Bluetooth devices
if (mBluetoothAdapter.startDiscovery()) {Log.e("disc", "print");
Toast.makeText(getApplicationContext(), "Discovering other bluetooth devices...", Toast.LENGTH_SHORT).show();
}
else {
Log.e("print", "print");
Toast.makeText(getApplicationContext(), "Discovery failed to start.", Toast.LENGTH_SHORT).show();
}
}
protected void makeDiscoverable(){
// Make local device discoverable
Intent discoverableIntent = new
Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, DISCOVERABLE_DURATION);
startActivityForResult(discoverableIntent, DISCOVERABLE_BT_REQUEST_CODE);
}
#Override
protected void onResume() {
super.onResume();
// Register the BroadcastReceiver for ACTION_FOUND
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(broadcastReceiver, filter);
}
#Override
protected void onPause() {
super.onPause();
this.unregisterReceiver(broadcastReceiver);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private class ListeningThread extends Thread {
private final BluetoothServerSocket bluetoothServerSocket;
public ListeningThread() {
BluetoothServerSocket temp = null;
try {
temp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(getString(R.string.app_name), uuid);
} catch (IOException e) {
e.printStackTrace();
}
bluetoothServerSocket = temp;
}
public void run() {
BluetoothSocket bluetoothSocket;
// This will block while listening until a BluetoothSocket is returned
// or an exception occurs
while (true) {
try {
Log.e("while", "over");
bluetoothSocket = bluetoothServerSocket.accept();
Log.e("bt", "accept");
} catch (IOException e) {Log.e("error", "catch");
break;
}
// If a connection is accepted
if (bluetoothSocket != null) {
Log.e("connection is accepted", "over");
BluetoothActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(BluetoothActivity.this, "Connected!", Toast.LENGTH_SHORT).show();
}
});
// Manage the connection in a separate thread
try {Log.e("callserver", "close");
bluetoothServerSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}//end of while
}
// Cancel the listening socket and terminate the thread
public void cancel() {
try {Log.e("cancel", "socket");
bluetoothServerSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
//Setting Up a Connecting Client
private class ConnectingThread extends Thread {
OutputStream mmOutputStream;
InputStream mmInputStream;
private final BluetoothSocket bluetoothSocket;
private final BluetoothDevice bluetoothDevice;
public ConnectingThread(BluetoothDevice device) {
BluetoothSocket temp = null;
bluetoothDevice = device;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try { Log.e("click6", "click6");
temp = bluetoothDevice.createRfcommSocketToServiceRecord(uuid);
} catch (IOException e) {
e.printStackTrace();
}
bluetoothSocket = temp;
}
public void run() {
// Cancel any discovery as it will slow down the connection
Log.e("click7", "click7");
mBluetoothAdapter.cancelDiscovery();
Log.e("click8", "click8");
try {
// This will block until it succeeds in connecting to the device
// through the bluetoothSocket or throws an exception
bluetoothSocket.connect();
mmOutputStream = bluetoothSocket.getOutputStream();
mmInputStream = bluetoothSocket.getInputStream();
beginListenForData();
Log.e("listendata", "lsitendata");
BluetoothActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(BluetoothActivity.this, "Connected with Device!", Toast.LENGTH_SHORT).show();
}
});
Log.e("click9", "click9");
} catch (IOException connectException) {
connectException.printStackTrace();
try {
bluetoothSocket.close();
Log.e("click6", "blueclose");
} catch (IOException closeException) {
closeException.printStackTrace();
}
}
}
void beginListenForData()
{
final Handler handler = new Handler();
final byte delimiter = 10; //This is the ASCII code for a newline character
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];//It uses a 1024 bytes long buffer because it doesn't have any way of knowing the length of the input stream.
workerThread = new Thread(new Runnable()
{
public void run()
{
while(!Thread.currentThread().isInterrupted() && !stopWorker)
{
try
{
int bytesAvailable = mmInputStream.available();
if(bytesAvailable > 0)
{
byte[] packetBytes = new byte[bytesAvailable];
mmInputStream.read(packetBytes);
for(int i=0;i<bytesAvailable;i++)
{
byte b = packetBytes[i];
if(b == delimiter)
{
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
handler.post(new Runnable()
{
public void run()
{
myLabel.setText(data);
}
});
}
else
{
readBuffer[readBufferPosition++] = b;
}
}
}
}
catch (IOException ex)
{
stopWorker = true;
}
}
}
});
workerThread.start();
}
Hi the app crashed when I try to call beginListenForData(); The error state that Can't create handler inside thread that has not called Looper.prepare()
Does anyone know what wrong? I am new to android. Please help.
Bluetooth.xml below
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context=".BluetoothActivity">
<ToggleButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textOn="Turn off Bluetooth"
android:textOff="Turn on Bluetooth"
android:id="#+id/toggleButton"
android:onClick="onToggle"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true" />
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/listView"
android:layout_alignParentStart="true"
android:layout_marginStart="76dp"
android:layout_below="#+id/toggleButton" />
<TextView
android:id="#+id/label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Type here:"
android:layout_below="#+id/toggleButton"
android:layout_centerHorizontal="true"
android:layout_marginTop="66dp" />
</RelativeLayout>

Try this inside beginListenForData()
Replace
final Handler handler = new Handler();
With this
final Handler handler = new Handler(Looper.getMainLooper());

Bluetooth android app Rfcomm connection

I wanted to start with the basics of bluetooth connection and make a simple app capable of scanning, pairing and connecting.
I'm struggling with the last concept, i followed a lot of tutorials but I couldn't make it. I don't know if you can help me but here is my code.
ublic class MainActivity extends Activity {
private final String TAG = "Debugging";
private final static int REQUEST_CODE_ENABLE_BLUETOOTH = 0;
protected static final int SUCCESS_CONNECT = 0;
protected static final int MESSAGE_READ = 1;
public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
BluetoothAdapter btAdapter;
ArrayList<String> arrayListpaired;
ArrayAdapter<String> listAdapter,adapter;
ListView listView,listViewPaired;
Set<BluetoothDevice> deviceArray;
ArrayList<String> pairedDevices;
IntentFilter filter;
BroadcastReceiver receiver;
BluetoothDevice bdDevice;
ArrayList<BluetoothDevice> arrayListBluetoothDevices = null;
ArrayList<BluetoothDevice> arrayListPairedBluetoothDevices;
ListItemClicked listItemClicked;
ListItemClickedonPaired listItemClickedonPaired;
String tag = "debugging";
Handler mHandler= new Handler() {
public void handleMessage(Message msg){
super.handleMessage(msg);
switch(msg.what){
case SUCCESS_CONNECT:
ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket)msg.obj);
Toast.makeText(getApplicationContext(),"Connect",Toast.LENGTH_LONG).show();
String s= "Succesfully connected";
connectedThread.write(s.getBytes());
Log.i(tag, "connected");
break;
case MESSAGE_READ:
byte[] readbuff=(byte[])msg.obj;
String string= readbuff.toString();
Toast.makeText(getApplicationContext(), string,Toast.LENGTH_SHORT).show();
break;
}
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btAdapter = BluetoothAdapter.getDefaultAdapter();
arrayListBluetoothDevices = new ArrayList<BluetoothDevice>();
arrayListpaired = new ArrayList<String>();
arrayListPairedBluetoothDevices = new ArrayList<BluetoothDevice>();
adapter= new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, arrayListpaired);
listItemClickedonPaired = new ListItemClickedonPaired();
listViewPaired = (ListView) findViewById(R.id.listView3);
listItemClicked = new ListItemClicked();
listView = (ListView) findViewById(R.id.listView2);
listAdapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_activated_1);
listView.setAdapter(listAdapter);
listAdapter.notifyDataSetChanged();
listViewPaired.setAdapter(adapter);
setupMessageButton1();
setupMessageButton2();
setupMessageButton3();
setupMessageButton4();
setupMessageButton5();
init();
getPairedDevices();
}
private void init() {
listView.setOnItemClickListener(listItemClicked);
listViewPaired.setOnItemClickListener(listItemClickedonPaired);
filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String Action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(Action)) {
Toast.makeText(getApplicationContext(), "One Device Found", Toast.LENGTH_SHORT).show();
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (arrayListBluetoothDevices.size() < 1) // this checks if the size of bluetooth device is 0,then add the
{ // device to the arraylist.
listAdapter.add(device.getName() + "\n" + device.getAddress());
arrayListBluetoothDevices.add(device);
listAdapter.notifyDataSetChanged();
}
else
{
boolean flag = true; // flag to indicate that particular device is already in the arlist or not
for (int i = 0; i < arrayListBluetoothDevices.size(); i++) {
if (device.getAddress().equals(arrayListBluetoothDevices.get(i).getAddress())) {
flag = false;
}
}
if (flag == true) {
listAdapter.add(device.getName() + "\n" + device.getAddress());
arrayListBluetoothDevices.add(device);
listAdapter.notifyDataSetChanged();
}
}
}
}
};
registerReceiver(receiver, filter);
}
private void createBond(BluetoothDevice btDevice){
try
{
Method method = btDevice.getClass().getMethod("createBond", (Class[]) null);
method.invoke(btDevice, (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 void getPairedDevices() {
Set<BluetoothDevice> pairedDevice = btAdapter.getBondedDevices();
if(pairedDevice.size()>0)
{
for(BluetoothDevice device : pairedDevice)
{
arrayListpaired.add(device.getName()+"\n"+device.getAddress());
arrayListPairedBluetoothDevices.add(device);
}
}
adapter.notifyDataSetChanged();
}
public class ListItemClicked implements OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
bdDevice = arrayListBluetoothDevices.get(position);
Log.i("Log", "The device : " + bdDevice.toString());
getPairedDevices();
createBond(bdDevice);
adapter.notifyDataSetChanged();
Log.i("Log", "The bond is created: with" + bdDevice.toString());
}
}
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
BluetoothSocket tmp = null;
mmDevice = device;
try {
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) { }
mmSocket = tmp;
}
public void run() {
btAdapter.cancelDiscovery();
try {
mmSocket.connect();
} catch (IOException connectException) {
try {
mmSocket.close();
} catch (IOException closeException) { }
return;
}
mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
buffer = new byte[1024];
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
} catch (IOException e) { }
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
#Override
protected void onDestroy() {
super.onDestroy();
btAdapter.cancelDiscovery();
unregisterReceiver(receiver);
}
class ListItemClickedonPaired implements OnItemClickListener
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
bdDevice = arrayListPairedBluetoothDevices.get(position);
unpairDevice(bdDevice);
//arrayListPairedBluetoothDevices.clear();
}
}
private void makeDiscoverable() {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 150);
startActivity(discoverableIntent);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
Toast.makeText(MainActivity.this, "Bluetooth must be enabled to start scanning", Toast.LENGTH_SHORT).show();
} else
{
Toast.makeText(MainActivity.this, "Click on TURN_OFF to disable bluetooth", Toast.LENGTH_LONG).show();
}
}
private void setupMessageButton1() {
//1.get a reference for my button
Button messageButton = (Button) findViewById(R.id.button1);
//2. Set the click to run my code
messageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
listAdapter.clear();
arrayListBluetoothDevices.clear();
btAdapter.startDiscovery();
}
});
}
private void setupMessageButton2() {
//1.get a reference to the button.
Button messageButton = (Button) findViewById(R.id.button2);
//2. set the click listener to run my code.
messageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (btAdapter.isEnabled()) {
listAdapter.clear();
btAdapter.disable();
} else
{
Toast.makeText(MainActivity.this, "Dont worry it's already off", Toast.LENGTH_SHORT).show();
}
}
});
}
private void setupMessageButton3() {
//1.get a reference for my button
Button messageButton = (Button) findViewById(R.id.button3);
//2. Set the click to run my code
messageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
finish();
}
});
}
private void setupMessageButton4() {
//1.get a reference for my button
Button messageButton = (Button) findViewById(R.id.button4);
//2. Set the click to run my code
messageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
btAdapter.enable();
}
});
}
private void setupMessageButton5() {
//1.get a reference for my button
Button messageButton = (Button) findViewById(R.id.button5);
//2. Set the click to run my code
messageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
makeDiscoverable();
}
});
}
}
Concerning the log i have that message :
"D/BluetoothUtils﹕ isSocketAllowedBySecurityPolicy start : device null"
"W/BluetoothAdapter﹕ getBluetoothService() called with no BluetoothManagerCallback"
"D/BluetoothSocket﹕ connect(), SocketState: INIT, mPfd: {ParcelFileDescriptor: FileDescriptor[75]} "
public class ListItemClicked implements OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
bdDevice = arrayListBluetoothDevices.get(position);
Log.i("Log", "The device : " + bdDevice.toString());
createBond(bdDevice);
adapter.notifyDataSetChanged();
ConnectThread connect = new ConnectThread(bdDevice);
connect.start();
}
}
For the connection, i use the ConnectThread found in Bluetooth APi developer Website:
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
BluetoothSocket tmp = null;
mmDevice = device;
try {
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) { }
mmSocket = tmp;
}
public void run() {
btAdapter.cancelDiscovery();
try {
mmSocket.connect();
} catch (IOException connectException) {
try {
mmSocket.close();
} catch (IOException closeException) { }
return;
}
mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}

it's ok i found the solution, i had the problem with the phone i'm using, he is not supporting SPP.
Thank you anyway

Reading a Bluetooth data stream from an Arduino with Android

The Situation
I'm trying to write an application that does one very simple task: when an NFC tag is detected with the appropriate AAR and URI it launches the application, uses data in the tag to connect to a specified Bluetooth radio (specified by the NFC tag) and waits to accept a data stream, which it converts to a string and displays on the screen.
When I run the application currently it simply exits immediately with three runtime exceptions. I would like it to wait passively instead of closing, and I do not understand the runtime exceptions.
The Exceptions
Unable to resume activity; NullPointerException
ParseTag(); exception line 127
onResume(); exception line 83
The Code
public class BlueNF extends Activity {
private BluetoothDevice mBluetoothDevice = null;
private BluetoothAdapter mBluetoothAdapter = null;
private BluetoothSocket mBluetoothSocket = null;
private NfcAdapter mNfcAdapter = null;
private NdefMessage dashTag = null;
private static final int REQUEST_ENABLE_BT = 3;
private static final UUID SerialPortServiceClass_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
private InputStream iStream = null;
public static String iValue = null;
public final static String EXTRA_MESSAGE = "com.yogafarts.hackpsuproject.BlueNF.iValue";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Set the content view
setContentView(R.layout.activity_blue_nf);
//Check for NFC
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (mNfcAdapter == null) {
Toast.makeText(this, "NFC is not available", Toast.LENGTH_LONG).show();
finish();
return;
}
//Check for Bluetooth
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
finish();
return;
}
}
#Override
public void onStart() {
super.onStart();
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
public void onResume() {
super.onResume();
//IntentFilter ndefTag = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
//Get the current intent
Intent dashTagIntent = getIntent();
//Read extra intent data into tag object (Really just reading the NdefMessage into the dashTag object
dashTag = dashTagIntent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
//Create a byte array of bluetooth hardware ID using ParseTag
byte[] mBluetoothInfo = ParseTag(dashTag);
//Create a bluetooth adapter object
mBluetoothDevice = mBluetoothAdapter.getRemoteDevice(mBluetoothInfo);//Should be 0013EF00061A
try {
mBluetoothSocket = mBluetoothDevice.createRfcommSocketToServiceRecord(SerialPortServiceClass_UUID);
}
catch ( IOException e ) {
Log.e( "Bluetooth Socket", "Bluetooth not available, or insufficient permissions" );
}
//Cancel discovery because it's resource intensive (if it's active)
mBluetoothAdapter.cancelDiscovery();
//Connect to the device
try {
mBluetoothSocket.connect();
iStream = mBluetoothSocket.getInputStream();
//System.out.println(iStream);
//OutputStream oStream = mBluetoothSocket.getOutputStream();
}
catch ( IOException e ) {
try { mBluetoothSocket.close();
}
catch ( IOException e2 ) {
Log.e( "Bluetooth Socket", "IO Exception" );
}
}
iValue = iStream.toString();
viewMessage();
}
public byte[] ParseTag(NdefMessage ndef) {
NdefRecord[] mNdef = ndef.getRecords();
return mNdef[2].getPayload();
}
public void viewMessage() {
Intent intent = new Intent(this, DisplayMessage.class);
//TextView text = (TextView) findViewById(R.id.tv);
String message = iValue;//text.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.blue_n, menu);
return true;
}
}
And the activity that displays the text after the stream is read...
public class DisplayMessage extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
TextView text = (TextView) findViewById(R.id.tv);
text.setText(com.yogafarts.hackpsuproject.BlueNF.iValue);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.display_message, menu);
return true;
}
}

Android + Pair devices via bluetooth programmatically

I want to discover bluetooth devices in range, list and pair to them on click. I used following code but its just closing application when I click on device name which I want to pair.
I want to know mistake in my code or any other way to do what i need.
package com.marakana;
import java.util.Set;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemClickListener;
public class BluetoothDemo extends Activity {
// Debugging
private static final String TAG = "DeviceListActivity";
private static final boolean D = true;
// Return Intent extra
public static String EXTRA_DEVICE_ADDRESS = "device_address";
// Member fields
private BluetoothAdapter mBtAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
private ArrayAdapter<String> mNewDevicesArrayAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Setup the window
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.device_list);
// Set result CANCELED incase the user backs out
setResult(Activity.RESULT_CANCELED);
// Initialize the button to perform device discovery
Button scanButton = (Button) findViewById(R.id.button_scan);
scanButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
doDiscovery();
v.setVisibility(View.GONE);
}
});
// Initialize array adapters. One for already paired devices and
// one for newly discovered devices
mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);
mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);
// Find and set up the ListView for paired devices
ListView pairedListView = (ListView) findViewById(R.id.paired_devices);
pairedListView.setAdapter(mPairedDevicesArrayAdapter);
pairedListView.setOnItemClickListener(mDeviceClickListener);
// Find and set up the ListView for newly discovered devices
ListView newDevicesListView = (ListView) findViewById(R.id.new_devices);
newDevicesListView.setAdapter(mNewDevicesArrayAdapter);
newDevicesListView.setOnItemClickListener(mDeviceClickListener);
// Register for broadcasts when a device is discovered
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(mReceiver, filter);
// Register for broadcasts when discovery has finished
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);
// Get the local Bluetooth adapter
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
// Get a set of currently paired devices
Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();
// If there are paired devices, add each one to the ArrayAdapter
if (pairedDevices.size() > 0) {
findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);
for (BluetoothDevice device : pairedDevices) {
mPairedDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
} else {
String noDevices = getResources().getText(R.string.none_paired).toString();
mPairedDevicesArrayAdapter.add(noDevices);
}
}
#Override
protected void onDestroy() {
super.onDestroy();
// Make sure we're not doing discovery anymore
if (mBtAdapter != null) {
mBtAdapter.cancelDiscovery();
}
// Unregister broadcast listeners
this.unregisterReceiver(mReceiver);
}
/**
* Start device discover with the BluetoothAdapter
*/
private void doDiscovery() {
if (D) Log.d(TAG, "doDiscovery()");
// Indicate scanning in the title
setProgressBarIndeterminateVisibility(true);
setTitle(R.string.scanning);
// Turn on sub-title for new devices
findViewById(R.id.title_new_devices).setVisibility(View.VISIBLE);
// If we're already discovering, stop it
if (mBtAdapter.isDiscovering()) {
mBtAdapter.cancelDiscovery();
}
// Request discover from BluetoothAdapter
mBtAdapter.startDiscovery();
}
// The on-click listener for all devices in the ListViews
private OnItemClickListener mDeviceClickListener = new OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) {
// Cancel discovery because it's costly and we're about to connect
mBtAdapter.cancelDiscovery();
// Get the device MAC address, which is the last 17 chars in the View
String info = ((TextView) v).getText().toString();
String address = info.substring(info.length() - 17);
// Create the result Intent and include the MAC address
Intent intent = new Intent();
intent.putExtra(EXTRA_DEVICE_ADDRESS, address);
// Set result and finish this Activity
setResult(Activity.RESULT_OK, intent);
finish();
}
};
// The BroadcastReceiver that listens for discovered devices and
// changes the title when discovery is finished
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// If it's already paired, skip it, because it's been listed already
if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
// When discovery is finished, change the Activity title
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
setProgressBarIndeterminateVisibility(false);
setTitle(R.string.select_device);
if (mNewDevicesArrayAdapter.getCount() == 0) {
String noDevices = getResources().getText(R.string.none_found).toString();
mNewDevicesArrayAdapter.add(noDevices);
}
}
}
};
}

In my first answer the logic is shown for those who want to go with the logic only.
I think I was not able to make clear to #chalukya3545, that's why I am adding the whole code to let him know the exact flow of the code.
BluetoothDemo.java
public class BluetoothDemo extends Activity {
ListView listViewPaired;
ListView listViewDetected;
ArrayList<String> arrayListpaired;
Button buttonSearch,buttonOn,buttonDesc,buttonOff;
ArrayAdapter<String> adapter,detectedAdapter;
static HandleSeacrh handleSeacrh;
BluetoothDevice bdDevice;
BluetoothClass bdClass;
ArrayList<BluetoothDevice> arrayListPairedBluetoothDevices;
private ButtonClicked clicked;
ListItemClickedonPaired listItemClickedonPaired;
BluetoothAdapter bluetoothAdapter = null;
ArrayList<BluetoothDevice> arrayListBluetoothDevices = null;
ListItemClicked listItemClicked;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listViewDetected = (ListView) findViewById(R.id.listViewDetected);
listViewPaired = (ListView) findViewById(R.id.listViewPaired);
buttonSearch = (Button) findViewById(R.id.buttonSearch);
buttonOn = (Button) findViewById(R.id.buttonOn);
buttonDesc = (Button) findViewById(R.id.buttonDesc);
buttonOff = (Button) findViewById(R.id.buttonOff);
arrayListpaired = new ArrayList<String>();
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
clicked = new ButtonClicked();
handleSeacrh = new HandleSeacrh();
arrayListPairedBluetoothDevices = new ArrayList<BluetoothDevice>();
/*
* the above declaration is just for getting the paired bluetooth devices;
* this helps in the removing the bond between paired devices.
*/
listItemClickedonPaired = new ListItemClickedonPaired();
arrayListBluetoothDevices = new ArrayList<BluetoothDevice>();
adapter= new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_1, arrayListpaired);
detectedAdapter = new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_single_choice);
listViewDetected.setAdapter(detectedAdapter);
listItemClicked = new ListItemClicked();
detectedAdapter.notifyDataSetChanged();
listViewPaired.setAdapter(adapter);
}
#Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
getPairedDevices();
buttonOn.setOnClickListener(clicked);
buttonSearch.setOnClickListener(clicked);
buttonDesc.setOnClickListener(clicked);
buttonOff.setOnClickListener(clicked);
listViewDetected.setOnItemClickListener(listItemClicked);
listViewPaired.setOnItemClickListener(listItemClickedonPaired);
}
private void getPairedDevices() {
Set<BluetoothDevice> pairedDevice = bluetoothAdapter.getBondedDevices();
if(pairedDevice.size()>0)
{
for(BluetoothDevice device : pairedDevice)
{
arrayListpaired.add(device.getName()+"\n"+device.getAddress());
arrayListPairedBluetoothDevices.add(device);
}
}
adapter.notifyDataSetChanged();
}
class ListItemClicked implements OnItemClickListener
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
bdDevice = arrayListBluetoothDevices.get(position);
//bdClass = arrayListBluetoothDevices.get(position);
Log.i("Log", "The dvice : "+bdDevice.toString());
/*
* here below we can do pairing without calling the callthread(), we can directly call the
* connect(). but for the safer side we must usethe threading object.
*/
//callThread();
//connect(bdDevice);
Boolean isBonded = false;
try {
isBonded = createBond(bdDevice);
if(isBonded)
{
//arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());
//adapter.notifyDataSetChanged();
getPairedDevices();
adapter.notifyDataSetChanged();
}
} catch (Exception e) {
e.printStackTrace();
}//connect(bdDevice);
Log.i("Log", "The bond is created: "+isBonded);
}
}
class ListItemClickedonPaired implements OnItemClickListener
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
bdDevice = arrayListPairedBluetoothDevices.get(position);
try {
Boolean removeBonding = removeBond(bdDevice);
if(removeBonding)
{
arrayListpaired.remove(position);
adapter.notifyDataSetChanged();
}
Log.i("Log", "Removed"+removeBonding);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/*private void callThread() {
new Thread(){
public void run() {
Boolean isBonded = false;
try {
isBonded = createBond(bdDevice);
if(isBonded)
{
arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());
adapter.notifyDataSetChanged();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}//connect(bdDevice);
Log.i("Log", "The bond is created: "+isBonded);
}
}.start();
}*/
private Boolean connect(BluetoothDevice bdDevice) {
Boolean bool = false;
try {
Log.i("Log", "service method is called ");
Class cl = Class.forName("android.bluetooth.BluetoothDevice");
Class[] par = {};
Method method = cl.getMethod("createBond", par);
Object[] args = {};
bool = (Boolean) method.invoke(bdDevice);//, args);// this invoke creates the detected devices paired.
//Log.i("Log", "This is: "+bool.booleanValue());
//Log.i("Log", "devicesss: "+bdDevice.getName());
} catch (Exception e) {
Log.i("Log", "Inside catch of serviceFromDevice Method");
e.printStackTrace();
}
return bool.booleanValue();
};
public boolean removeBond(BluetoothDevice btDevice)
throws Exception
{
Class btClass = Class.forName("android.bluetooth.BluetoothDevice");
Method removeBondMethod = btClass.getMethod("removeBond");
Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);
return returnValue.booleanValue();
}
public boolean createBond(BluetoothDevice btDevice)
throws Exception
{
Class class1 = Class.forName("android.bluetooth.BluetoothDevice");
Method createBondMethod = class1.getMethod("createBond");
Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);
return returnValue.booleanValue();
}
class ButtonClicked implements OnClickListener
{
#Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.buttonOn:
onBluetooth();
break;
case R.id.buttonSearch:
arrayListBluetoothDevices.clear();
startSearching();
break;
case R.id.buttonDesc:
makeDiscoverable();
break;
case R.id.buttonOff:
offBluetooth();
break;
default:
break;
}
}
}
private BroadcastReceiver myReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Message msg = Message.obtain();
String action = intent.getAction();
if(BluetoothDevice.ACTION_FOUND.equals(action)){
Toast.makeText(context, "ACTION_FOUND", Toast.LENGTH_SHORT).show();
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
try
{
//device.getClass().getMethod("setPairingConfirmation", boolean.class).invoke(device, true);
//device.getClass().getMethod("cancelPairingUserInput", boolean.class).invoke(device);
}
catch (Exception e) {
Log.i("Log", "Inside the exception: ");
e.printStackTrace();
}
if(arrayListBluetoothDevices.size()<1) // this checks if the size of bluetooth device is 0,then add the
{ // device to the arraylist.
detectedAdapter.add(device.getName()+"\n"+device.getAddress());
arrayListBluetoothDevices.add(device);
detectedAdapter.notifyDataSetChanged();
}
else
{
boolean flag = true; // flag to indicate that particular device is already in the arlist or not
for(int i = 0; i<arrayListBluetoothDevices.size();i++)
{
if(device.getAddress().equals(arrayListBluetoothDevices.get(i).getAddress()))
{
flag = false;
}
}
if(flag == true)
{
detectedAdapter.add(device.getName()+"\n"+device.getAddress());
arrayListBluetoothDevices.add(device);
detectedAdapter.notifyDataSetChanged();
}
}
}
}
};
private void startSearching() {
Log.i("Log", "in the start searching method");
IntentFilter intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
BluetoothDemo.this.registerReceiver(myReceiver, intentFilter);
bluetoothAdapter.startDiscovery();
}
private void onBluetooth() {
if(!bluetoothAdapter.isEnabled())
{
bluetoothAdapter.enable();
Log.i("Log", "Bluetooth is Enabled");
}
}
private void offBluetooth() {
if(bluetoothAdapter.isEnabled())
{
bluetoothAdapter.disable();
}
}
private void makeDiscoverable() {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
Log.i("Log", "Discoverable ");
}
class HandleSeacrh extends Handler
{
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 111:
break;
default:
break;
}
}
}
}
Here is the main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="#+id/buttonOn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="On"/>
<Button
android:id="#+id/buttonDesc"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Make Discoverable"/>
<Button
android:id="#+id/buttonSearch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Search"/>
<Button
android:id="#+id/buttonOff"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Bluetooth Off"/>
<ListView
android:id="#+id/listViewPaired"
android:layout_width="match_parent"
android:layout_height="120dp">
</ListView>
<ListView
android:id="#+id/listViewDetected"
android:layout_width="match_parent"
android:layout_height="match_parent">
</ListView>
</LinearLayout>
Add this permissions to your AndroidManifest.xml file:
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
The output for this code will look like this.

The Best way is do not use any pairing code.
Instead of onClick go to other function or other class where You create the socket using UUID.
Android automatically pops up for pairing if already not paired.
or see this link for better understanding
Below is code for the same:
private OnItemClickListener mDeviceClickListener = new OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) {
// Cancel discovery because it's costly and we're about to connect
mBtAdapter.cancelDiscovery();
// Get the device MAC address, which is the last 17 chars in the View
String info = ((TextView) v).getText().toString();
String address = info.substring(info.length() - 17);
// Create the result Intent and include the MAC address
Intent intent = new Intent();
intent.putExtra(EXTRA_DEVICE_ADDRESS, address);
// Set result and finish this Activity
setResult(Activity.RESULT_OK, intent);
// **add this 2 line code**
Intent myIntent = new Intent(view.getContext(), Connect.class);
startActivityForResult(myIntent, 0);
finish();
}
};
Connect.java file is :
public class Connect extends Activity {
private static final String TAG = "zeoconnect";
private ByteBuffer localByteBuffer;
private InputStream in;
byte[] arrayOfByte = new byte[4096];
int bytes;
public BluetoothDevice mDevice;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.connect);
try {
setup();
} catch (ZeoMessageException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ZeoMessageParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void setup() throws ZeoMessageException, ZeoMessageParseException {
// TODO Auto-generated method stub
getApplicationContext().registerReceiver(receiver,
new IntentFilter(BluetoothDevice.ACTION_ACL_CONNECTED));
getApplicationContext().registerReceiver(receiver,
new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED));
BluetoothDevice zee = BluetoothAdapter.getDefaultAdapter().
getRemoteDevice("**:**:**:**:**:**");// add device mac adress
try {
sock = zee.createRfcommSocketToServiceRecord(
UUID.fromString("*******************")); // use unique UUID
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Log.d(TAG, "++++ Connecting");
try {
sock.connect();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Log.d(TAG, "++++ Connected");
try {
in = sock.getInputStream();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Log.d(TAG, "++++ Listening...");
while (true) {
try {
bytes = in.read(arrayOfByte);
Log.d(TAG, "++++ Read "+ bytes +" bytes");
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Log.d(TAG, "++++ Done: test()");
}}
private static final LogBroadcastReceiver receiver = new LogBroadcastReceiver();
public static class LogBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context paramAnonymousContext, Intent paramAnonymousIntent) {
Log.d("ZeoReceiver", paramAnonymousIntent.toString());
Bundle extras = paramAnonymousIntent.getExtras();
for (String k : extras.keySet()) {
Log.d("ZeoReceiver", " Extra: "+ extras.get(k).toString());
}
}
};
private BluetoothSocket sock;
#Override
public void onDestroy() {
getApplicationContext().unregisterReceiver(receiver);
if (sock != null) {
try {
sock.close();
} catch (IOException e) {
e.printStackTrace();
}
}
super.onDestroy();
}
}

if you have the BluetoothDevice object you can create bond(pair) from api 19 onwards with bluetoothDevice.createBond() method.
Edit
for callback, if the request was accepted or denied you will have to create a BroadcastReceiver with BluetoothDevice.ACTION_BOND_STATE_CHANGED action

Edit: I have just explained logic to pair here. If anybody want to go with the complete code then see my another answer. I have answered here for logic only but I was not able to explain properly, So I have added another answer in the same thread.
Try this to do pairing:
If you are able to search the devices then this would be your next step
ArrayList<BluetoothDevice> arrayListBluetoothDevices = NEW ArrayList<BluetoothDevice>;
I am assuming that you have the list of Bluetooth devices added in the arrayListBluetoothDevices:
BluetoothDevice bdDevice;
bdDevice = arrayListBluetoothDevices.get(PASS_THE_POSITION_TO_GET_THE_BLUETOOTH_DEVICE);
Boolean isBonded = false;
try {
isBonded = createBond(bdDevice);
if(isBonded)
{
Log.i("Log","Paired");
}
} catch (Exception e)
{
e.printStackTrace();
}
The createBond() method:
public boolean createBond(BluetoothDevice btDevice)
throws Exception
{
Class class1 = Class.forName("android.bluetooth.BluetoothDevice");
Method createBondMethod = class1.getMethod("createBond");
Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);
return returnValue.booleanValue();
}
Add this line into your Receiver in the ACTION_FOUND
if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
arrayListBluetoothDevices.add(device);
}