This code is a Bluetooth service, but I get NullPointerException when connect thread calls and I don't know how to receive data from Bluetooth service to update UI (handle message).
I want that this service runs in background and save received data in the database. I am a beginner and can not solve it.
BluetoothService.java
public class BluetoothService extends Service{
private Handler myHandler = null;
private int state;
BluetoothDevice myDevice;
ConnectThread connectThread;
ConnectedThread connectedThread;
private final IBinder mIBinder = new LocalBinder();
BluetoothAdapter mBluetoothAdapter;
/*public BluetoothService(Handler handler, BluetoothDevice device) {
state = Constants.STATE_NONE;
myHandler = handler;
myDevice = device;
}*/
@Override
public void onCreate()
{
super.onCreate();
}
@Override
public int onStartCommand(Intent intent, int flag, int startId) {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter != null) {
myDevice = (BluetoothDevice) intent.getExtras().get(Constants.EXTRA_DEVICE);
String deviceName = myDevice.getName();
String macAddress = myDevice.getAddress();
if (macAddress != null && macAddress.length() > 0) {
connect(myDevice);
} else {
stopSelf();
}
}
return START_STICKY;
}
public void onDestroy()
{
if(myHandler != null)
{
myHandler = null;
}
}
public IBinder onBind(Intent intent)
{
return mIBinder;
}
public class LocalBinder extends Binder
{
public BluetoothService getInstance()
{
return BluetoothService.this;
}
}
public void setHandler(Handler handler)
{
myHandler = handler;
}
public synchronized void connect(BluetoothDevice myDevice) {
Log.d(Constants.TAG, "Connecting to: " + myDevice.getName() + " - " + myDevice.getAddress());
// Start the thread to connect with the given device
setState(Constants.STATE_CONNECTING);
connectThread = new ConnectThread(myDevice);
connectThread.start();
}
public synchronized void stop() {
cancelConnectThread();
cancelConnectedThread();
setState(Constants.STATE_NONE);
}
private synchronized void setState(int state) {
Log.d(Constants.TAG, "setState() " + this.state + " -> " + state);
this.state = state;
// Give the new state to the Handler so the UI Activity can update
myHandler.obtainMessage(Constants.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
}
public synchronized int getState() {
return state;
}
public synchronized void connected(BluetoothSocket socket, BluetoothDevice device) {
Log.d(Constants.TAG, "connected to: " + device.getName());
cancelConnectThread();
// Start the thread to manage the connection and perform transmissions
connectedThread = new ConnectedThread(socket);
connectedThread.start();
setState(Constants.STATE_CONNECTED);
}
/**
* Indicate that the connection attempt failed and notify the UI Activity.
*/
private void connectionFailed() {
Log.e(Constants.TAG, "Connection Failed");
// Send a failure item_message back to the Activity
Message msg = myHandler.obtainMessage(Constants.MESSAGE_SNACKBAR);
Bundle bundle = new Bundle();
bundle.putString(Constants.SNACKBAR, "Unable to connect");
msg.setData(bundle);
myHandler.sendMessage(msg);
setState(Constants.STATE_ERROR);
cancelConnectThread();
}
/**
* Indicate that the connection was lost and notify the UI Activity.
*/
private void connectionLost() {
Log.e(Constants.TAG, "Connection Lost");
// Send a failure item_message back to the Activity
Message msg = myHandler.obtainMessage(Constants.MESSAGE_SNACKBAR);
Bundle bundle = new Bundle();
bundle.putString(Constants.SNACKBAR, "Cconnection was lost");
msg.setData(bundle);
myHandler.sendMessage(msg);
setState(Constants.STATE_ERROR);
cancelConnectedThread();
}
private void cancelConnectThread() {
// Cancel the thread that completed the connection
if (connectThread != null) {
connectThread.cancel();
connectThread = null;
}
}
private void cancelConnectedThread() {
// Cancel any thread currently running a connection
if (connectedThread != null) {
connectedThread.cancel();
connectedThread = null;
}
}
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (state != Constants.STATE_CONNECTED) {
Log.e(Constants.TAG, "Trying to send but not connected");
return;
}
r = connectedThread;
}
// Perform the write unsynchronized
r.write(out);
}
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
// Use a temporary object that is later assigned to mmSocket,
// because mmSocket is final
BluetoothSocket tmp = null;
mmDevice = device;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try {
// MY_UUID is the app's UUID string, also used by the server code
UUID uuid = Constants.myUUID;
tmp = device.createRfcommSocketToServiceRecord(uuid);
} catch (IOException e) {
Log.e(Constants.TAG, "Create RFcomm socket failed", e);
}
mmSocket = tmp;
}
public void run() {
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
Log.e(Constants.TAG, "Unable to connect", connectException);
try {
mmSocket.close();
} catch (IOException closeException) {
Log.e(Constants.TAG, "Unable to close() socket during connection failure", closeException);
}
connectionFailed();
return;
}
synchronized (BluetoothService.this) {
connectThread = null;
}
// Do work to manage the connection (in a separate thread)
connected(mmSocket, mmDevice);
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(Constants.TAG, "Close() socket failed", e);
}
}
}
public 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) {
Log.e(Constants.TAG, "Temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
Log.i(Constants.TAG, "Begin connectedThread");
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
StringBuilder readMessage = new StringBuilder();
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
bytes = mmInStream.read(buffer);
String read = new String(buffer, 0, bytes);
readMessage.append(read);
if (read.contains("\n")) {
myHandler.obtainMessage(Constants.MESSAGE_READ, bytes, -1, readMessage.toString()).sendToTarget();
readMessage.setLength(0);
}
} catch (Exception e) {
Log.e(Constants.TAG, "Connection Lost", e);
connectionLost();
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
myHandler.obtainMessage(Constants.MESSAGE_WRITE, -1, -1, bytes).sendToTarget();
} catch (IOException e) {
Log.e(Constants.TAG, "Exception during write", e);
}
}
/* Call this from the main activity to shutdown the connection */
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(Constants.TAG, "close() of connect socket failed", e);}
}
}
}
Main.java
public class Main extends AppCompatActivity {
BluetoothDevice device;
static BluetoothService bluetoothService;
static TextView T2;
Button button;
static ImageView UVBorder;
static ImageView TempBorder;
static ImageView UVStatus;
static ImageView TempStatus;
ImageView UVChart;
ImageView TempChart;
static TextView UVValue;
static TextView TempValue;
TextView UVLable;
TextView TempLable;
static int SAFE_STATUS=R.drawable.ok;
static int NEED_CARE_STATUS=R.drawable.need_care;
static int AT_RISK_STATUS=R.drawable.alert;
//ProgressDialog progressDlg;
//private static ArrayAdapter<String> mConversationArrayAdapter;
//private ListView mConversationView;
private int time_interval = 2000;
private long oldCurrentTimeMillis;
static String username;
private Toolbar toolbar;
private NavigationView navigationView;
private DrawerLayout drawerLayout;
static PulsatorLayout mPulsator1;
static PulsatorLayout mPulsator2;
private BluetoothService mService = null;
private boolean mIsBound;
myHandler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_view);
UVStatus=(ImageView) findViewById(R.id.uv_stat);
TempStatus=(ImageView) findViewById(R.id.temp_stat);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
User CurrentUser = UserHolder.getInstance().getUser();
device = getIntent().getExtras().getParcelable(Constants.EXTRA_DEVICE);
myHandler handler = new myHandler(Main.this);
///bluetoothService = new BluetoothService(handler, device);
Intent intent=new Intent(this.getBaseContext(), BluetoothService.class);
intent.putExtra(Constants.EXTRA_DEVICE, device);
startService(intent);
doBindService();
}
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder)
{
mService = ((BluetoothService.LocalBinder)iBinder).getInstance();
mService.setHandler(handler);
}
@Override
public void onServiceDisconnected(ComponentName componentName)
{
mService = null;
}
};
private void doBindService()
{
// Establish a connection with the service. We use an explicit
// class name because we want a specific service implementation that
// we know will be running in our own process (and thus won't be
// supporting component replacement by other applications).
bindService(new Intent(this,
BluetoothService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
private void doUnbindService()
{
if (mIsBound)
{
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
@Override
protected void onDestroy()
{
super.onDestroy();
doUnbindService();
}
@Override protected void onStart() {
super.onStart();
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mReceiver, filter);
// bluetoothService.connect();
}
@Override protected void onStop() {
super.onStop();
if (bluetoothService != null) {
bluetoothService.stop();
Log.d(Constants.TAG, "Stopping");
}
unregisterReceiver(mReceiver);
}
private static class myHandler extends Handler {
private final WeakReference<Main> mActivity;
public myHandler(Main activity) {
mActivity = new WeakReference<Main>(activity);
}
// @Override
public void handleMessage(Message msg) {
final Main activity = mActivity.get();
switch (msg.what) {
case Constants.MESSAGE_READ:
Packet packet=new Packet();
User CurrentUser = UserHolder.getInstance().getUser();
String username=CurrentUser.getUsername();
packet.setUserName(username);
int site_id=CurrentUser.getSite().getId();
packet.setSiteId(site_id);
String readMessage = (String) msg.obj;
// mConversationArrayAdapter.add(readMessage);
Log.e("msg",readMessage);
//run a asynctask
break;
}
}
}
}
@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) {
int id = item.getItemId();
return super.onOptionsItemSelected(item);
}}
