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How can i make bluetooth connection in every Activity?

I am developing an app which sends data to the android with Bluetooth. I can send data and see from the ardunio side. I can connect the device but when I go to the another activity in the app connection has been lost. How can I keep connection open? In the Second class I can connected the device and send the data, if I have another activity how can i use active Bluetooth connection and send data?
private String mConnectedDeviceName = null;
private StringBuffer mOutStringBuffer;
private BluetoothAdapter mBluetoothAdapter = null;
private BluetoothChatService mChatService = null;
#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
FragmentActivity activity = getActivity();
if (mBluetoothAdapter == null && activity != null) {
Toast.makeText(activity, "Bluetooth is not available", Toast.LENGTH_LONG).show();
activity.finish();
}
}
#Override
public void onStart() {
super.onStart();
if (mBluetoothAdapter == null) {
return;
}
// If BT is not on, request that it be enabled.
// setupChat() will then be called during onActivityResult
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the chat session
} else if (mChatService == null) {
setupChat();
}
}
#Override
public void onDestroy() {
super.onDestroy();
if (mChatService != null) {
mChatService.stop();
}
}
#Override
public void onResume() {
super.onResume();
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 View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_bluetooth_chat, container, false);
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
rad_saat = view.findViewById(R.id.rad_saat);
rad_Co2 = view.findViewById(R.id.rad_CO2);
rad_sicaklik = view.findViewById(R.id.rad_sicaklik);
rad_Manuel = view.findViewById(R.id.rad_manuel);
opn_spinner = view.findViewById(R.id.spn_options);
radioGroup = view.findViewById(R.id.radioGroup);
spnCrd_Options = view.findViewById(R.id.spnCrd_Options);
crd_GonderButton = view.findViewById(R.id.crd_GonderButton);
txt_GonderButton = view.findViewById(R.id.txt_GonderButton);
rad_saat.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkButton();
}
});
rad_Co2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkButton();
}
});
rad_sicaklik.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkButton();
}
});
rad_Manuel.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkButton();
}
});
radioGroup.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkButton();
}
});
crd_GonderButton.setOnClickListener(new View.OnClickListener() {
#RequiresApi(api = Build.VERSION_CODES.O)
#Override
public void onClick(View v) {
sendButton();
}
});
txt_GonderButton.setOnClickListener(new View.OnClickListener() {
#RequiresApi(api = Build.VERSION_CODES.O)
#Override
public void onClick(View v) {
sendButton();
}
});
}
private void setupChat() {
Log.d(TAG, "setupChat()");
// Initialize the array adapter for the conversation thread
FragmentActivity activity = getActivity();
if (activity == null) {
return;
}
// Initialize the BluetoothChatService to perform bluetooth connections
mChatService = new BluetoothChatService(activity, mHandler);
// Initialize the buffer for outgoing messages
mOutStringBuffer = new StringBuffer();
}
private void ensureDiscoverable() {
if (mBluetoothAdapter.getScanMode() !=
BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
}
}
public void sendMessage(String message) {
// Check that we're actually connected before trying anything
if (mChatService.getState() != BluetoothChatService.STATE_CONNECTED) {
Toast.makeText(getActivity(), R.string.not_connected, Toast.LENGTH_SHORT).show();
return;
}
// Check that there's actually something to send
if (message.length() > 0) {
// Get the message bytes and tell the BluetoothChatService to write
byte[] send = message.getBytes();
mChatService.write(send);
// Reset out string buffer to zero and clear the edit text field
mOutStringBuffer.setLength(0);
}
}
private TextView.OnEditorActionListener mWriteListener
= new TextView.OnEditorActionListener() {
public boolean onEditorAction(TextView view, int actionId, KeyEvent event) {
// If the action is a key-up event on the return key, send the message
if (actionId == EditorInfo.IME_NULL && event.getAction() == KeyEvent.ACTION_UP) {
String message = view.getText().toString();
sendMessage(message);
}
return true;
}
};
private void setStatus(int resId) {
FragmentActivity activity = getActivity();
if (null == activity) {
return;
}
final ActionBar actionBar = activity.getActionBar();
if (null == actionBar) {
return;
}
actionBar.setSubtitle(resId);
}
private void setStatus(CharSequence subTitle) {
FragmentActivity activity = getActivity();
if (null == activity) {
return;
}
final ActionBar actionBar = activity.getActionBar();
if (null == actionBar) {
return;
}
actionBar.setSubtitle(subTitle);
}
private void messageHandler()
{
}
public void checkButton(){
saatList = new ArrayList<String>(Arrays.asList(new String[]{"00:00 - 03:00","03:00 -06:00 ","06:00 - 09:00","09:00 - 12:00","12:00 - 15:00","15:00 - 18:00","18:00 - 21:00","21:00 - 00:00"}));
manuelList = new ArrayList<String>(Arrays.asList(new String[]{"KAPALI","AÇIK"}));
if(rad_saat.isChecked()){
atananList = saatList;
spnCrd_Options.setVisibility(View.VISIBLE);
opn_spinner.setVisibility(View.VISIBLE);
}
if(rad_Manuel.isChecked()){
atananList = manuelList;
spnCrd_Options.setVisibility(View.VISIBLE);
opn_spinner.setVisibility(View.VISIBLE);
}
if(rad_Co2.isChecked()){
opn_spinner.setVisibility(View.GONE);
spnCrd_Options.setVisibility(View.GONE);
}
if(rad_sicaklik.isChecked()){
opn_spinner.setVisibility(View.GONE);
spnCrd_Options.setVisibility(View.GONE);
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_spinner_item, atananList);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
opn_spinner.setAdapter(adapter);
}
#RequiresApi(api = Build.VERSION_CODES.O)
public void sendButton() {
System.out.println("1. Bluettoth adapter" + mBluetoothAdapter);
modelClass = new ModelClass();
modelClass.setmBluetoothAdapter(mBluetoothAdapter);
modelClass.setmChatService(mChatService);
modelClass.setmConnectedDeviceName(mConnectedDeviceName);
modelClass.setmOutStringBuffer(mOutStringBuffer);
Intent intent = new Intent(getActivity(), SendCordinates.class);
startActivity(intent);
}
/**
* The Handler that gets information back from the BluetoothChatService
*/
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:
setStatus(getString(R.string.title_connected_to, mConnectedDeviceName));
//textViewReceived.setText("Received:");
break;
case BluetoothChatService.STATE_CONNECTING:
setStatus(R.string.title_connecting);
break;
case BluetoothChatService.STATE_LISTEN:
case BluetoothChatService.STATE_NONE:
setStatus(R.string.title_not_connected);
break;
}
break;
case Constants.MESSAGE_WRITE:
break;
case Constants.MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
receiveBuffer += readMessage;
if(receiveBuffer.contains("\n")) {
receiveBuffer = receiveBuffer.substring(0, receiveBuffer.length() - 1);
messageHandler();
receiveBuffer = "";
}
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();
}
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) {
connectDevice(data, true);
}
break;
case REQUEST_CONNECT_DEVICE_INSECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
connectDevice(data, false);
}
break;
case REQUEST_ENABLE_BT:
// When the request to enable Bluetooth returns
if (resultCode == Activity.RESULT_OK) {
// Bluetooth is now enabled, so set up a chat session
setupChat();
} else {
// User did not enable Bluetooth or an error occurred
Log.d(TAG, "BT not enabled");
FragmentActivity activity = getActivity();
if (activity != null) {
Toast.makeText(activity, R.string.bt_not_enabled_leaving,
Toast.LENGTH_SHORT).show();
activity.finish();
}
}
}
}
private void connectDevice(Intent data, boolean secure) {
// Get the device MAC address
Bundle extras = data.getExtras();
if (extras == null) {
return;
}
String address = extras.getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
// Get the BluetoothDevice object
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
// Attempt to connect to the device
mChatService.connect(device, secure);
}
#Override
public void onCreateOptionsMenu(#NonNull Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.bluetooth_chat, menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.secure_connect_scan: {
// Launch the DeviceListActivity to see devices and do scan
Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class);
startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_SECURE);
return true;
}
case R.id.discoverable: {
// Ensure this device is discoverable by others
ensureDiscoverable();
return true;
}
}
return false;
}
public class BluetoothChatService {
private static final String TAG = "BluetoothChatService";
private static final String NAME_SECURE = "BluetoothChatSecure";
private static final String NAME_INSECURE = "BluetoothChatInsecure";
private static final UUID MY_UUID_SECURE =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
private static final UUID MY_UUID_INSECURE =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Member fields
private final BluetoothAdapter mAdapter;
private final Handler mHandler;
private AcceptThread mSecureAcceptThread;
private AcceptThread mInsecureAcceptThread;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private int mState;
private int mNewState;
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_LISTEN = 1; // now listening for incoming connections
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
public BluetoothChatService(Context context, Handler handler) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
mState = STATE_NONE;
mNewState = mState;
mHandler = handler;
}
private synchronized void updateUserInterfaceTitle() {
mState = getState();
Log.d(TAG, "updateUserInterfaceTitle() " + mNewState + " -> " + mState);
mNewState = mState;
// Give the new state to the Handler so the UI Activity can update
mHandler.obtainMessage(Constants.MESSAGE_STATE_CHANGE, mNewState, -1).sendToTarget();
}
public synchronized int getState() {
return mState;
}
public synchronized void start() {
Log.d(TAG, "start");
// Cancel any thread attempting to make a connection
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
// Start the thread to listen on a BluetoothServerSocket
if (mSecureAcceptThread == null) {
mSecureAcceptThread = new AcceptThread(true);
mSecureAcceptThread.start();
}
if (mInsecureAcceptThread == null) {
mInsecureAcceptThread = new AcceptThread(false);
mInsecureAcceptThread.start();
}
// Update UI title
updateUserInterfaceTitle();
}
public synchronized void connect(BluetoothDevice device, boolean secure) {
Log.d(TAG, "connect to: " + device);
// Cancel any thread attempting to make a connection
if (mState == STATE_CONNECTING) {
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
}
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
mConnectThread = new ConnectThread(device, secure);
mConnectThread.start();
// Update UI title
updateUserInterfaceTitle();
}
public synchronized void connected(BluetoothSocket socket, BluetoothDevice
device, final String socketType) {
Log.d(TAG, "connected, Socket Type:" + socketType);
// Cancel the thread that completed the connection
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
if (mSecureAcceptThread != null) {
mSecureAcceptThread.cancel();
mSecureAcceptThread = null;
}
if (mInsecureAcceptThread != null) {
mInsecureAcceptThread.cancel();
mInsecureAcceptThread = null;
}
mConnectedThread = new ConnectedThread(socket, socketType);
mConnectedThread.start();
Message msg = mHandler.obtainMessage(Constants.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(Constants.DEVICE_NAME, device.getName());
msg.setData(bundle);
mHandler.sendMessage(msg);
// Update UI title
updateUserInterfaceTitle();
}
public synchronized void stop() {
Log.d(TAG, "stop");
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
if (mSecureAcceptThread != null) {
mSecureAcceptThread.cancel();
mSecureAcceptThread = null;
}
if (mInsecureAcceptThread != null) {
mInsecureAcceptThread.cancel();
mInsecureAcceptThread = null;
}
mState = STATE_NONE;
// Update UI title
updateUserInterfaceTitle();
}
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (mState != STATE_CONNECTED) return;
r = mConnectedThread;
}
// Perform the write unsynchronized
r.write(out);
}
private void connectionFailed() {
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(Constants.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(Constants.TOAST, "Unable to connect device");
msg.setData(bundle);
mHandler.sendMessage(msg);
mState = STATE_NONE;
// Update UI title
updateUserInterfaceTitle();
// Start the service over to restart listening mode
BluetoothChatService.this.start();
}
private void connectionLost() {
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(Constants.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(Constants.TOAST, "Device connection was lost");
msg.setData(bundle);
mHandler.sendMessage(msg);
mState = STATE_NONE;
// Update UI title
updateUserInterfaceTitle();
// Start the service over to restart listening mode
BluetoothChatService.this.start();
}
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket mmServerSocket;
private String mSocketType;
public AcceptThread(boolean secure) {
BluetoothServerSocket tmp = null;
mSocketType = secure ? "Secure" : "Insecure";
try {
if (secure) {
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME_SECURE,
MY_UUID_SECURE);
} else {
tmp = mAdapter.listenUsingInsecureRfcommWithServiceRecord(
NAME_INSECURE, MY_UUID_INSECURE);
}
} catch (IOException e) {
Log.e(TAG, "Socket Type: " + mSocketType + "listen() failed", e);
}
mmServerSocket = tmp;
mState = STATE_LISTEN;
}
public void run() {
Log.d(TAG, "Socket Type: " + mSocketType +
"BEGIN mAcceptThread" + this);
setName("AcceptThread" + mSocketType);
BluetoothSocket socket;
while (mState != STATE_CONNECTED) {
try {
// This is a blocking call and will only return on a
// successful connection or an exception
socket = mmServerSocket.accept();
} catch (IOException e) {
Log.e(TAG, "Socket Type: " + mSocketType + "accept() failed", e);
break;
}
if (socket != null) {
synchronized (BluetoothChatService.this) {
switch (mState) {
case STATE_LISTEN:
case STATE_CONNECTING:
// Situation normal. Start the connected thread.
connected(socket, socket.getRemoteDevice(),
mSocketType);
break;
case STATE_NONE:
case STATE_CONNECTED:
// Either not ready or already connected. Terminate new socket.
try {
socket.close();
} catch (IOException e) {
Log.e(TAG, "Could not close unwanted socket", e);
}
break;
}
}
}
}
Log.i(TAG, "END mAcceptThread, socket Type: " + mSocketType);
}
public void cancel() {
Log.d(TAG, "Socket Type" + mSocketType + "cancel " + this);
try {
mmServerSocket.close();
} catch (IOException e) {
Log.e(TAG, "Socket Type" + mSocketType + "close() of server failed", e);
}
}
}
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
private String mSocketType;
public ConnectThread(BluetoothDevice device, boolean secure) {
mmDevice = device;
BluetoothSocket tmp = null;
mSocketType = secure ? "Secure" : "Insecure";
try {
if (secure) {
tmp = device.createRfcommSocketToServiceRecord(
MY_UUID_SECURE);
} else {
tmp = device.createInsecureRfcommSocketToServiceRecord(
MY_UUID_INSECURE);
}
} catch (IOException e) {
Log.e(TAG, "Socket Type: " + mSocketType + "create() failed", e);
}
mmSocket = tmp;
mState = STATE_CONNECTING;
}
public void run() {
Log.i(TAG, "BEGIN mConnectThread SocketType:" + mSocketType);
setName("ConnectThread" + mSocketType);
// Always cancel discovery because it will slow down a connection
mAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
// This is a blocking call and will only return on a
// successful connection or an exception
mmSocket.connect();
} catch (IOException e) {
// Close the socket
try {
mmSocket.close();
} catch (IOException e2) {
Log.e(TAG, "unable to close() " + mSocketType +
" socket during connection failure", e2);
}
connectionFailed();
return;
}
synchronized (BluetoothChatService.this) {
mConnectThread = null;
}
// Start the connected thread
connected(mmSocket, mmDevice, mSocketType);
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect " + mSocketType + " socket failed", e);
}
}
}
/**
* This thread runs during a connection with a remote device.
* It handles all incoming and outgoing transmissions.
*/
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket, String socketType) {
Log.d(TAG, "create ConnectedThread: " + socketType);
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
mState = STATE_CONNECTED;
}
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (mState == STATE_CONNECTED) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(Constants.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
break;
}
}
}
/**
* Write to the connected OutStream.
*
* #param buffer The bytes to write
*/
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
// Share the sent message back to the UI Activity
mHandler.obtainMessage(Constants.MESSAGE_WRITE, -1, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Exception during write", e);
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}

Create an actual service which can be bound from multiple activities.
class BluetoothService : Service() {
private val binder = LocalBinder()
override fun onBind(intent: Intent): IBinder? {
return binder
}
inner class LocalBinder : Binder() {
fun getService() : BluetoothService {
return this#BluetoothService
}
}
}
private var bluetoothService : BluetoothService? = null
private val serviceConnection: ServiceConnection = object : ServiceConnection {
override fun onServiceConnected(componentName: ComponentName, service:IBinder) {
bluetoothService = (service as LocalBinder).getService()
bluetoothService?.let { bluetooth ->
// ...
}
}
override fun onServiceDisconnected(componentName: ComponentName) {
bluetoothService = null
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val serviceIntent = Intent(this, BluetootService::class.java)
bindService(serviceIntent, serviceConnection, Context.BIND_AUTO_CREATE)
}
See BLE case for the inspiration.

Have you ever tried to use something like dagger? You can create a repository that you istantiate at the start of application.
Then if you need to use it in activity you can inject it with something like this:
#Inject lateinit var bluetoothRepository: BluetoothRepository

Bluetooth Connection between LeJOS EV3 and Android

I'm having trouble connecting my smartphone to my EV3 over bluetooth using an app.
My situation:
I'm developing an App to send simple Strings to the EV3 which runs with leJOS 0.9.1-aplu11.
My Problem is, I'm not really familiar with Bluetooth, so my app or my receiver-software doesn't work as well.
My goal:
My goal is to create a Listener on the EV3 which is permanant listening for Strings from the app and an App that sends the strings when I press a button.
I hope you can help me.
I'm from germany so don't wonder about my beautifull writing skills!
Here is my Code:
App:
public class MainActivity extends AppCompatActivity {
private final static String TAG = "MainActivity";
private BluetoothAdapter mBluetoothAdapter;
private static BluetoothDevice mDevice;
private Button mSendBN;
private final static String MY_UUID = "00001101-0000-1000-8000-00805f9b34fb";
private static BluetoothSocket mSocket = null;
private static String mMessage = "Stop";
private static PrintStream sender;
private void findBrick() {
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter
.getBondedDevices();
for (BluetoothDevice device : pairedDevices) {
if (device.getName().equals("EV3"))
this.mDevice = device;
}
}
private void initBluetooth() {
Log.d(TAG, "Checking Bluetooth...");
if (mBluetoothAdapter == null) {
Log.d(TAG, "Device does not support Bluetooth");
mSendBN.setClickable(false);
} else {
Log.d(TAG, "Bluetooth supported");
}
if (!mBluetoothAdapter.isEnabled()) {
mSendBN.setClickable(false);
Log.d(TAG, "Bluetooth not enabled");
} else {
Log.d(TAG, "Bluetooth enabled");
}
}
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Toast.makeText(this, "SpeechRecognizer gestartet", Toast.LENGTH_SHORT).show();
setContentView(R.layout.activity_main);
mSendBN = (Button) findViewById(R.id.button);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
initBluetooth();
findBrick();
if (mDevice == null) {
mSendBN.setClickable(false);
Toast.makeText(this, "No Devices found or BT disabled", Toast.LENGTH_SHORT).show();
Log.d("onC", "Connected to " + mDevice);
}
try {
createSocket();
} catch (IOException e) {
e.printStackTrace();
}
startService();
}
private void startService() {
if (PermissionHandler.checkPermission(this, PermissionHandler.RECORD_AUDIO)) {
Intent i = new Intent(this, BackgroundRecognizerService.class);
startService(i);
}
}
public void onRequestPermissionResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == PermissionHandler.RECORD_AUDIO && grantResults.length > 0) {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
startService();
}
}
}
public static void onSend(View view) throws IOException {
try {
OutputStream os = mSocket.getOutputStream();
sender = new PrintStream(os);
Log.d("onSend", "Message = " + mMessage);
sender.println(mMessage);
sender.flush();
Log.d("onSend", "Message sent");
mSocket.close();
Log.d("onSend", "Socket closed");
} catch (IllegalStateException | NullPointerException e) {
e.printStackTrace();
}
}
public void createSocket() throws IOException {
try {
UUID uuid = UUID.fromString(MY_UUID);
mSocket = mDevice.createRfcommSocketToServiceRecord(uuid);
} catch (IOException e) {
e.printStackTrace();
}
Log.d("createSocket", "Adapter");
BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
mSocket.connect();
OutputStream os = mSocket.getOutputStream();
sender = new PrintStream(os);
Log.d("createSocket", "Fertig, " + "Socket: " + mSocket + " Sender: " + sender + " OutputStream: " + os + " mDevice: " + mDevice.getName());
}
protected void onDestroy() {
super.onDestroy();
Log.d("onDestroy", "App beendet");
try {
mSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
Log.d("onDestroy", "App vollständig beendet");
}
}
EV3:
public class BTJ {
public static void main(String[] args) {
BTConnector connector = new BTConnector();
System.out.println("0. Auf Signal warten");
NXTConnection conn = connector.waitForConnection(0, NXTConnection.RAW);
InputStream is = conn.openInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String message = "";
while (true){
System.out.println("1. Schleife gestartet");
message = "";
try {
message = br.readLine();
System.out.println("2. Message: " + message);
} catch (IOException e) {
e.printStackTrace(System.out);
}
}
}
}

I have the answer..!
public class BTJ {
public static void main(String[] args) {
BTConnector connector = new BTConnector();
System.out.println("0. Auf Signal warten");
NXTConnection conn = connector.waitForConnection(0, NXTConnection.RAW);
InputStream is = conn.openInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is), 1);
String message = "";
while (true){
System.out.println("1. Schleife gestartet");
message = "";
try {
message = br.readLine();
System.out.println("2. Message: " + message);
} catch (IOException e) {
e.printStackTrace(System.out);
}
}
}

How to prevent Bluetooth Disconnected when moving Fragment

I make a POS in android. I want to make a printing in my apps. To do printing I'm using bluetooth printer. Then, I had success make the bluetooth connection and I make it in one fragment. But every time I move to another fragment the bluetooth connction will be disconnected. How can I prevent bluetooth disconnect when moving fragment?
SettingFragment.Java
/**
* A simple {#link Fragment} subclass.
*/
public class SettingFragment extends Fragment {
public static final int MESSAGE_STATE_CHANGE = 1;
public static final int MESSAGE_READ = 2;
public static final int MESSAGE_WRITE = 3;
public static final int MESSAGE_DEVICE_NAME = 4;
public static final int MESSAGE_TOAST = 5;
public static final int MESSAGE_CONNECTION_LOST = 6;
public static final int MESSAGE_UNABLE_CONNECT = 7;
private String mConnectedDeviceName = null;
// Key names received from the BluetoothService Handler
public static final String DEVICE_NAME = "device_name";
public static final String TOAST = "toast";
// Intent request codes
private static final int REQUEST_CONNECT_DEVICE = 1;
private static final int REQUEST_ENABLE_BT = 2;
private BluetoothAdapter mBluetoothAdapter = null;
private BluetoothService mService = null;
private static final String CHINESE = "GBK";
SessionManagement sessionManagement;
DatabaseHandler db;
TextView tvConnected;
Button btnScan;
Button btnTest;
public SettingFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootview = inflater.inflate(R.layout.fragment_setting, container, false);
getActivity().setTitle("Setting");
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
btnScan = (Button)rootview.findViewById(R.id.btnScan);
btnTest = (Button) rootview.findViewById(R.id.btnTest);
tvConnected = (TextView) rootview.findViewById(R.id.tvPrinterConnect);
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(
BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the session
} else {
if (mService == null)
KeyListenerInit();
}
return rootview;
}
#SuppressLint("HandlerLeak")
private final Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
if (DEBUG)
Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1);
switch (msg.arg1) {
case BluetoothService.STATE_CONNECTED:
//btnScan.setText(getText(R.string.Connecting));
btnScan.setEnabled(false);
break;
case BluetoothService.STATE_CONNECTING:
Toast.makeText((MainActivity)getContext(),R.string.title_connecting,Toast.LENGTH_SHORT).show();
break;
case BluetoothService.STATE_LISTEN:
case BluetoothService.STATE_NONE:
Toast.makeText((MainActivity)getContext(),R.string.title_not_connected,Toast.LENGTH_SHORT).show();
break;
}
break;
case MESSAGE_WRITE:
break;
case MESSAGE_READ:
break;
case MESSAGE_DEVICE_NAME:
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
Toast.makeText(getActivity(),
"Connected to " + mConnectedDeviceName,
Toast.LENGTH_SHORT).show();
tvConnected.setText("Connected to "+mConnectedDeviceName );
break;
case MESSAGE_TOAST:
Toast.makeText(getActivity(),
msg.getData().getString(TOAST), Toast.LENGTH_SHORT)
.show();
break;
case MESSAGE_CONNECTION_LOST:
Toast.makeText(getActivity(), "Device connection was lost",
Toast.LENGTH_SHORT).show();
tvConnected.setText("Not Connect to Any Device");
// editText.setEnabled(false);
// sendButton.setEnabled(false);
break;
case MESSAGE_UNABLE_CONNECT:
Toast.makeText(getActivity(), "Unable to connect device",
Toast.LENGTH_SHORT).show();
break;
}
}
};
#Override
public void onStart() {
super.onStart();
// If Bluetooth is not on, request that it be enabled.
// setupChat() will then be called during onActivityResult
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(
BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the session
} else {
if (mService == null)
KeyListenerInit();
}
}
#Override
public synchronized void onResume() {
super.onResume();
if (mService != null) {
if (mService.getState() == BluetoothService.STATE_NONE) {
// Start the Bluetooth services
mService.start();
}
}
}
#Override
public synchronized void onPause() {
super.onPause();
if (DEBUG)
Log.e(TAG, "- ON PAUSE -");
}
#Override
public void onStop() {
super.onStop();
if (DEBUG)
Log.e(TAG, "-- ON STOP --");
}
#Override
public void onDestroy() {
super.onDestroy();
// Stop the Bluetooth services
if (mService != null)
mService.stop();
if (DEBUG)
Log.e(TAG, "--- ON DESTROY ---");
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (DEBUG)
Log.d(TAG, "onActivityResult " + resultCode);
switch (requestCode) {
case REQUEST_CONNECT_DEVICE:{
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
// Get the device MAC address
String address = data.getExtras().getString(
DeviceListActivity.EXTRA_DEVICE_ADDRESS);
// Get the BLuetoothDevice object
if (BluetoothAdapter.checkBluetoothAddress(address)) {
BluetoothDevice device = mBluetoothAdapter
.getRemoteDevice(address);
// Attempt to connect to the device
mService.connect(device);
}
}
break;
}
case REQUEST_ENABLE_BT:{
// When the request to enable Bluetooth returns
if (resultCode == Activity.RESULT_OK) {
// Bluetooth is now enabled, so set up a session
KeyListenerInit();
} else {
// User did not enable Bluetooth or an error occured
Log.d(TAG, "BT not enabled");
Toast.makeText(getActivity(), R.string.bt_not_enabled_leaving,
Toast.LENGTH_SHORT).show();
getActivity().onBackPressed();
}
break;
}
}
}
private void KeyListenerInit() {
btnScan.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class);
startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE);
}
});
mService = new BluetoothService(getActivity(), mHandler);
}
}
BluetoothService.JAVA
public class BluetoothService {
// Debugging
private static final String TAG = "BluetoothService";
private static final boolean DEBUG = true;
// Name for the SDP record when creating server socket
private static final String NAME = "ZJPrinter";
//UUID must be this
// Unique UUID for this application
private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Member fields
private BluetoothAdapter mAdapter;
private Handler mHandler;
private AcceptThread mAcceptThread;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private int mState;
// Constants that indicate the current connection state
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_LISTEN = 1; // now listening for incoming connections
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
public static String ErrorMessage = "No_Error_Message";
/**
* Constructor. Prepares a new BTPrinter session.
* #param context The UI Activity Context
* #param handler A Handler to send messages back to the UI Activity
*/
public BluetoothService(Context context, Handler handler) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
mState = STATE_NONE;
mHandler = handler;
}
/**
* Set the current state of the connection
* #param state An integer defining the current connection state
*/
private synchronized void setState(int state) {
if (DEBUG) Log.d(TAG, "setState() " + mState + " -> " + state);
mState = state;
// Give the new state to the Handler so the UI Activity can update
mHandler.obtainMessage(SettingFragment.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
}
/**
* Return the current connection state. */
public synchronized int getState() {
return mState;
}
/**
* Start the service. Specifically start AcceptThread to begin a
* session in listening (server) mode. Called by the Activity onResume() */
public synchronized void start() {
if (DEBUG) Log.d(TAG, "start");
// Cancel any thread attempting to make a connection
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
// Start the thread to listen on a BluetoothServerSocket
if (mAcceptThread == null) {
mAcceptThread = new AcceptThread();
mAcceptThread.start();
}
setState(STATE_LISTEN);
}
/**
* Start the ConnectThread to initiate a connection to a remote device.
* #param device The BluetoothDevice to connect
*/
public synchronized void connect(BluetoothDevice device) {
if (DEBUG) Log.d(TAG, "connect to: " + device);
// Cancel any thread attempting to make a connection
if (mState == STATE_CONNECTING) {
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
// Start the thread to connect with the given device
mConnectThread = new ConnectThread(device);
mConnectThread.start();
setState(STATE_CONNECTING);
}
/**
* Start the ConnectedThread to begin managing a Bluetooth connection
* #param socket The BluetoothSocket on which the connection was made
* #param device The BluetoothDevice that has been connected
*/
public synchronized void connected(BluetoothSocket socket, BluetoothDevice device) {
if (DEBUG) Log.d(TAG, "connected");
// Cancel the thread that completed the connection
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
// Cancel the accept thread because we only want to connect to one device
if (mAcceptThread != null) {mAcceptThread.cancel(); mAcceptThread = null;}
// Start the thread to manage the connection and perform transmissions
mConnectedThread = new ConnectedThread(socket);
mConnectedThread.start();
// Send the name of the connected device back to the UI Activity
Message msg = mHandler.obtainMessage(SettingFragment.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(SettingFragment.DEVICE_NAME, device.getName());
msg.setData(bundle);
mHandler.sendMessage(msg);
setState(STATE_CONNECTED);
}
/**
* Stop all threads
*/
public synchronized void stop() {
if (DEBUG) Log.d(TAG, "stop");
setState(STATE_NONE);
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
if (mAcceptThread != null) {mAcceptThread.cancel(); mAcceptThread = null;}
}
/**
* Write to the ConnectedThread in an unsynchronized manner
* #param out The bytes to write
* #see ConnectedThread#write(byte[])
*/
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (mState != STATE_CONNECTED) return;
r = mConnectedThread;
}
r.write(out);
}
/**
* Indicate that the connection attempt failed and notify the UI Activity.
*/
private void connectionFailed() {
setState(STATE_LISTEN);
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(SettingFragment.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(SettingFragment.TOAST, "Unable to connect device");
msg.setData(bundle);
mHandler.sendMessage(msg);
}
/**
* Indicate that the connection was lost and notify the UI Activity.
*/
private void connectionLost() {
//setState(STATE_LISTEN);
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(SettingFragment.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(SettingFragment.TOAST, "Device connection was lost");
msg.setData(bundle);
mHandler.sendMessage(msg);
}
/**
* This thread runs while listening for incoming connections. It behaves
* like a server-side client. It runs until a connection is accepted
* (or until cancelled).
*/
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket mmServerSocket;
public AcceptThread() {
BluetoothServerSocket tmp = null;
// Create a new listening server socket
try {
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
} catch (IOException e) {
Log.e(TAG, "listen() failed", e);
}
mmServerSocket = tmp;
}
#Override
public void run() {
if (DEBUG) Log.d(TAG, "BEGIN mAcceptThread" + this);
setName("AcceptThread");
BluetoothSocket socket = null;
// Listen to the server socket if we're not connected
while (mState != STATE_CONNECTED) {
try {
// This is a blocking call and will only return on a
// successful connection or an exception
socket = mmServerSocket.accept();
} catch (IOException e) {
Log.e(TAG, "accept() failed", e);
break;
}
// If a connection was accepted
if (socket != null) {
synchronized (BluetoothService.this) {
switch (mState) {
case STATE_LISTEN:
case STATE_CONNECTING:
// Situation normal. Start the connected thread.
connected(socket, socket.getRemoteDevice());
break;
case STATE_NONE:
case STATE_CONNECTED:
// Either not ready or already connected. Terminate new socket.
try {
socket.close();
} catch (IOException e) {
Log.e(TAG, "Could not close unwanted socket", e);
}
break;
}
}
}
}
if (DEBUG) Log.i(TAG, "END mAcceptThread");
}
public void cancel() {
if (DEBUG) Log.d(TAG, "cancel " + this);
try {
mmServerSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of server failed", e);
}
}
}
/**
* This thread runs while attempting to make an outgoing connection
* with a device. It runs straight through; the connection either
* succeeds or fails.
*/
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
mmDevice = device;
BluetoothSocket tmp = null;
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
Log.e(TAG, "create() failed", e);
}
mmSocket = tmp;
}
#Override
public void run() {
Log.i(TAG, "BEGIN mConnectThread");
setName("ConnectThread");
// Always cancel discovery because it will slow down a connection
mAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
// This is a blocking call and will only return on a
// successful connection or an exception
mmSocket.connect();
} catch (IOException e) {
connectionFailed();
// Close the socket
try {
mmSocket.close();
} catch (IOException e2) {
Log.e(TAG, "unable to close() socket during connection failure", e2);
}
// Start the service over to restart listening mode
BluetoothService.this.start();
return;
}
// Reset the ConnectThread because we're done
synchronized (BluetoothService.this) {
mConnectThread = null;
}
// Start the connected thread
connected(mmSocket, mmDevice);
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}
/**
* This thread runs during a connection with a remote device.
* It handles all incoming and outgoing transmissions.
*/
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(TAG, "create ConnectedThread");
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
#Override
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
byte[] buffer = new byte[256];
// Read from the InputStream
bytes = mmInStream.read(buffer);
if(bytes>0)
{
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(SettingFragment.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
}
else
{
Log.e(TAG, "disconnected");
connectionLost();
//add by chongqing jinou
if(mState != STATE_NONE)
{
Log.e(TAG, "disconnected");
// Start the service over to restart listening mode
BluetoothService.this.start();
}
break;
}
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
//add by chongqing jinou
if(mState != STATE_NONE)
{
// Start the service over to restart listening mode
BluetoothService.this.start();
}
break;
}
}
}
/**
* Write to the connected OutStream.
* #param buffer The bytes to write
*/
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
mmOutStream.flush();//清空缓存
/* if (buffer.length > 3000) //
{
byte[] readata = new byte[1];
SPPReadTimeout(readata, 1, 5000);
}*/
Log.i("BTPWRITE", new String(buffer,"GBK"));
// Share the sent message back to the UI Activity
mHandler.obtainMessage(SettingFragment.MESSAGE_WRITE, -1, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Exception during write", e);
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}
}

Not getting proper voltage reading from my OBDII reading app

I'm working on a OBDII reading app to read basic data such as (in this case) voltage. I've tried other apps and it works just fine to read the voltage of the OBDII adapter, so there's nothing wrong with the adapter itself.
I'm using the OBDII api from pires on github. When connection to my OBDII via Bluetooth successfully I get 0,0V and after that I get a Error saying: "Error running 01 42, response: ...UNABLETOCONNECT" (you can see this in the log cat below)
BTHandler.java
public class BTHandler {
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
final ArrayList<String> devices = new ArrayList();
private final Handler mHandler;
private BluetoothAdapter mAdapter;
private BluetoothDevice device;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private BluetoothSocket socket;
private String status;
private int pPlatform = Constants.SPA;
private int mState;
private boolean connectionStatus = false;
public BTHandler(Context context, Handler handler) { // Konstruktor
mAdapter = BluetoothAdapter.getDefaultAdapter();
mHandler = handler;
}
public void write(String s) {
mConnectedThread.sendRawCommand(s);
Log.v("write", "write");
}
public void connect(String deviceAddress) {
mConnectThread = new ConnectThread(deviceAddress);
mConnectThread.start();
}
private void guiHandler(int what, int arg1, String obj) {
Message msg = mHandler.obtainMessage();
msg.what = what;
msg.obj = obj;
msg.arg1 = arg1;
msg.sendToTarget();
}
private class ConnectThread extends Thread {
BluetoothSocket tmp = null;
private BluetoothSocket mmSocket;
public ConnectThread(String deviceAddress) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
device = mAdapter.getRemoteDevice(deviceAddress);
BluetoothAdapter mAdapter = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice device = mAdapter.getRemoteDevice(deviceAddress);
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
try {
tmp = device.createRfcommSocketToServiceRecord(uuid);
//socket.connect();
//Log.v("connect", "connect");
} catch (IOException e) {
//e.printStackTrace();
//Log.v("exception", "e");
}
mmSocket = tmp;
}
public void run() {
// Cancel discovery because it will slow down the connection
mAdapter.cancelDiscovery();
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes;
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
Log.v("connect", "connect");
} catch (IOException connectException) {
Log.v("connectException", "e");
try {
mmSocket.close();
Log.v("close", "close");
} catch (IOException closeException) {
Log.v("closeException", "e");
}
guiHandler(Constants.TOAST, Constants.SHORT, "Connection Failed");
return;
}
guiHandler(Constants.CONNECTION_STATUS, Constants.STATE_CONNECTED, "");
mConnectedThread = new ConnectedThread(mmSocket);
mConnectedThread.start();
}
}
private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private BluetoothSocket mmSocket;
private ObdMultiCommand multiCommand;
public ConnectedThread(BluetoothSocket socket) {
connectionStatus = true;
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
switch (pPlatform) {
case Constants.SPA:
multiCommand = new ObdMultiCommand();
multiCommand.add(new OdbRawCommand(SPA.VOLTAGE));
break;
}
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.v("e", "e");
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
OBDcmds();
// Keep listening to the InputStream until an exception occurs
try {
ModuleVoltageCommand voltageCommand = new ModuleVoltageCommand();
while (!Thread.currentThread().isInterrupted()) {
//System.out.println("Inside while");
// TODO handle commands result
Log.d("d", "Voltage: " + voltageCommand.getFormattedResult());
try {
voltageCommand.run(mmInStream, mmOutStream);
voltageCommand.getFormattedResult();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("inside catch before while");
}
// Get the input and output streams, using temp objects because
// member streams are final
/*
try {
ModuleVoltageCommand voltageCommand = new ModuleVoltageCommand();
while (!Thread.currentThread().isInterrupted()) {
voltageCommand.run(mmSocket.getInputStream(), mmSocket.getOutputStream());
voltageCommand.getFormattedResult();
Log.d("Log", "Voltage:" + voltageCommand.getFormattedResult());
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
*/
//ModuleVoltageCommand voltageCommand = new ModuleVoltageCommand();
/*while (!Thread.currentThread().isInterrupted()) {
try {
voltageCommand.run(socket.getInputStream(), socket.getOutputStream());
voltageCommand.getCalculatedResult();
Log.d("Log", "Voltage:" + voltageCommand.getResultUnit());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}*/
}
private void OBDcmds() { // execute commands
try {
new EchoOffCommand().run(mmInStream, mmOutStream);
new LineFeedOffCommand().run(mmInStream, mmOutStream);
new TimeoutCommand(100).run(mmInStream, mmOutStream);
new SelectProtocolCommand(ObdProtocols.AUTO).run(mmInStream, mmOutStream);
//ISO_15765_4_CAN
} catch (Exception e) {
Log.v("OBDcmds", "e");
// handle errors
}
}
// CALL this to MainActivity
public void sendRawCommand(String s) {
try {
} catch (Exception e) {
Log.v("sendRawCommand", "e");
}
}
/*
// 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) {
}
}
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
Button b1;
BluetoothAdapter mAdapter;
FragmentHostCallback mHost;
BTHandler btHandler;
private Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case Constants.MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BTHandler.STATE_CONNECTED:
setContentView(R.layout.activity_connected);
Toast.makeText(getApplicationContext(), R.string.title_connected_to, Toast.LENGTH_SHORT).show();
Log.v("Log", "Connected");
break;
case BTHandler.STATE_NONE:
Toast.makeText(getApplicationContext(), R.string.title_not_connected, Toast.LENGTH_SHORT).show();
break;
}
}
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btHandler = new BTHandler(MainActivity.this, mHandler);
b1 = (Button) findViewById(R.id.connect);
b1.setOnClickListener(this);
mAdapter = BluetoothAdapter.getDefaultAdapter();
//init();
if (mAdapter == null) {
Toast.makeText(getApplicationContext(), R.string.device_not_supported, Toast.LENGTH_LONG).show();
finish();
} else {
if (!mAdapter.isEnabled()) {
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(intent, 1);
}
}
//BTHandler btHandler = new BTHandler(MainActivity.this, mHandler);
//btHandler.connect("");
}
public void onClick(View v) {
int id = v.getId();
//String voltage = ("ATRV");
switch (id) {
case R.id.connect:
onConnect(); //Operation
Log.v("Log", "Pressed onClick");
break;
case R.id.getValue:
btHandler.write(SPA.VOLTAGE);
Log.v("getValue","" + SPA.VOLTAGE);
break;
}
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
Toast.makeText(getApplicationContext(), R.string.enable_bluetooth, Toast.LENGTH_SHORT).show();
finish();
}
}
private void onConnect() {
ArrayList deviceStrs = new ArrayList();
final ArrayList<String> devices = new ArrayList();
BluetoothAdapter mAdapter = BluetoothAdapter.getDefaultAdapter();
Set pairedDevices = mAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (Object device : pairedDevices) {
BluetoothDevice bdevice = (BluetoothDevice) device;
deviceStrs.add(bdevice.getName() + "\n" + bdevice.getAddress());
devices.add(bdevice.getAddress());
}
}
// show list
final AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.select_dialog_singlechoice,
deviceStrs.toArray(new String[deviceStrs.size()]));
alertDialog.setSingleChoiceItems(adapter, -1, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
int position = ((AlertDialog) dialog).getListView().getCheckedItemPosition();
String deviceAddress = devices.get(position);
btHandler.connect(deviceAddress);
//btHandler.write();
}
});
alertDialog.setTitle("Paired devices");
alertDialog.show();
}
#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);
}
}
Constants.java
public interface Constants {
int MESSAGE_STATE_CHANGE = 1;
int TOAST = 1;
int SHORT = 0;
int STATE_CONNECTED = 3;
int CONNECTION_STATUS = 1;
int MESSAGE_DEVICE_NAME = 4;
String DEVICE_NAME = "device_name";
int SPA = 1;
}
SPA.java
public interface SPA {
String VOLTAGE = "AT RV";
}

How do I initiate my BluetoothHandler to another (several) activity?

I'm making a OBDII Bluetooth Android app and i'm having some issues sending out commands. I've already made a successfully connection between my mobile device and my OBDII adapter, but when I click on another activity, the Bluetooth connection seems to quit?
When you open up the app you'll see a button that says "Connect Device". When you press that, a ListAdapter will show up with paired Bluetooth devices. Then when you have succesfully connected to the device (OBDII Adapter) it will take you to another layout where there is 3 activities that are 3 different powerplatforms for cars. This is where the problem occurs. For now, I just want to be able to read the voltage from the OBDII. But when I click my button getValue inside one of the 3 activities. I get an logcat error. And I think it's because I haven't initiated my BluetoothHandler properly. I have no idea how to do this.
MainActivity:
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
Button b1;
BluetoothAdapter mAdapter;
FragmentHostCallback mHost;
BTHandler btHandler;
private Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case Constants.MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BTHandler.STATE_CONNECTED:
//setContentView(R.layout.activity_connected);
Intent intent = new Intent(MainActivity.this, Connected.class);
startActivity(intent);
Toast.makeText(getApplicationContext(), R.string.title_connected_to, Toast.LENGTH_SHORT).show();
Log.v("Log", "Connected");
break;
case BTHandler.STATE_NONE:
Toast.makeText(getApplicationContext(), R.string.title_not_connected, Toast.LENGTH_SHORT).show();
break;
}
}
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btHandler = new BTHandler(MainActivity.this, mHandler);
b1 = (Button) findViewById(R.id.connect);
b1.setOnClickListener(this);
mAdapter = BluetoothAdapter.getDefaultAdapter();
//init();
if (mAdapter == null) {
Toast.makeText(getApplicationContext(), R.string.device_not_supported, Toast.LENGTH_LONG).show();
finish();
} else {
if (!mAdapter.isEnabled()) {
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(intent, 1);
}
}
//BTHandler btHandler = new BTHandler(MainActivity.this, mHandler);
//btHandler.connect("");
}
public void onClick(View v) {
int id = v.getId();
//String voltage = ("ATRV");
switch (id) {
case R.id.connect:
onConnect(); //Operation
Log.v("Log", "Pressed onClick");
break;
/*case R.id.getValue:
btHandler.write(voltage);
Log.v("Log", "getValue" + voltage);
break;*/
}
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
Toast.makeText(getApplicationContext(), R.string.enable_bluetooth, Toast.LENGTH_SHORT).show();
finish();
}
}
private void onConnect() {
ArrayList deviceStrs = new ArrayList();
final ArrayList<String> devices = new ArrayList();
BluetoothAdapter mAdapter = BluetoothAdapter.getDefaultAdapter();
Set pairedDevices = mAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (Object device : pairedDevices) {
BluetoothDevice bdevice = (BluetoothDevice) device;
deviceStrs.add(bdevice.getName() + "\n" + bdevice.getAddress());
devices.add(bdevice.getAddress());
}
}
// show list
final AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.select_dialog_singlechoice,
deviceStrs.toArray(new String[deviceStrs.size()]));
alertDialog.setSingleChoiceItems(adapter, -1, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
int position = ((AlertDialog) dialog).getListView().getCheckedItemPosition();
String deviceAddress = devices.get(position);
btHandler.connect(deviceAddress);
//btHandler.write();
}
});
alertDialog.setTitle("Paired devices");
alertDialog.show();
}
BTHandler:
public class BTHandler {
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
final ArrayList<String> devices = new ArrayList();
private final Handler mHandler;
private BluetoothAdapter mAdapter;
private BluetoothDevice device;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private BluetoothSocket socket;
private String status;
private int mState;
private boolean connectionStatus = false;
public BTHandler(Context context, Handler handler) { // Konstruktor
mAdapter = BluetoothAdapter.getDefaultAdapter();
mHandler = handler;
}
public void write(String s) {
mConnectedThread.sendRawCommand(s);
Log.v("write", "write");
}
/*
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
} catch (IOException e) {
}
}
*/
public void connect(String deviceAddress) {
mConnectThread = new ConnectThread(deviceAddress);
mConnectThread.start();
}
private void guiHandler(int what, int arg1, String obj) {
Message msg = mHandler.obtainMessage();
msg.what = what;
msg.obj = obj;
msg.arg1 = arg1;
msg.sendToTarget();
}
private class ConnectThread extends Thread {
BluetoothSocket tmp = null;
private BluetoothSocket mmSocket;
public ConnectThread(String deviceAddress) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
device = mAdapter.getRemoteDevice(deviceAddress);
BluetoothAdapter mAdapter = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice device = mAdapter.getRemoteDevice(deviceAddress);
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
try {
tmp = device.createRfcommSocketToServiceRecord(uuid);
//socket.connect();
//Log.v("connect", "connect");
} catch (IOException e) {
//e.printStackTrace();
//Log.v("exception", "e");
}
mmSocket = tmp;
}
public void run() {
// Cancel discovery because it will slow down the connection
mAdapter.cancelDiscovery();
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes;
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
Log.v("connect", "connect");
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
try {
mmSocket.close();
Log.v("close", "close");
} catch (IOException closeException) {
}
guiHandler(Constants.TOAST, Constants.SHORT, "Connection Failed");
return;
}
guiHandler(Constants.CONNECTION_STATUS, Constants.STATE_CONNECTED, "");
mConnectedThread = new ConnectedThread(mmSocket);
mConnectedThread.start();
}
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private ObdMultiCommand multiCommand;
public ConnectedThread(BluetoothSocket socket) {
connectionStatus = true;
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
try {
//RPMCommand engineRpmCommand = new RPMCommand();
//SpeedCommand speedCommand = new SpeedCommand();
ModuleVoltageCommand voltageCommand = new ModuleVoltageCommand();
while (!Thread.currentThread().isInterrupted()) {
//engineRpmCommand.run(mmInStream, mmOutStream); //(socket.getInputStream(), socket.getOutputStream());
//speedCommand.run(mmInStream, mmOutStream); //(socket.getInputStream(), socket.getOutputStream());
voltageCommand.run(socket.getInputStream(), socket.getOutputStream());
// TODO handle commands result
//Log.d("Log", "RPM: " + engineRpmCommand.getFormattedResult());
//Log.d("Log", "Speed: " + speedCommand.getFormattedResult());
Log.v("Log", "Voltage: " + voltageCommand.getFormattedResult());
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void run() {
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
OBDcmds();
// Keep listening to the InputStream until an exception occurs
while (connectionStatus) {
sendMultiCommand();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
// CALL this to MainActivity
public void sendRawCommand(String command) {
try {
new OdbRawCommand(command);
} catch (Exception e) {
Log.v("sendRawCommand", "e");
}
}
private void OBDcmds() { // execute commands
try {
new EchoOffCommand().run(socket.getInputStream(), socket.getOutputStream());
new LineFeedOffCommand().run(socket.getInputStream(), socket.getOutputStream());
new TimeoutCommand(100).run(socket.getInputStream(), socket.getOutputStream());
new SelectProtocolCommand(ObdProtocols.AUTO).run(socket.getInputStream(), socket.getOutputStream()); //ISO_15765_4_CAN
} catch (Exception e) {
Log.v("OBDcmds", "e");
// handle errors
}
}
/*
// 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) {
}
}
public void sendMultiCommand() {
try {
// RUN some code here
} catch (Exception e) {
}
}
}
}
SPA: One of the power platforms mentioned before.
public class SPA extends AppCompatActivity implements View.OnClickListener {
Button b2;
BTHandler btHandler;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sp);
b2 = (Button) findViewById(R.id.getValue);
b2.setOnClickListener(this);
}
public void onClick(View v) {
int id = v.getId();
String voltage = ("AT RV");
switch (id) {
case R.id.getValue:
btHandler.write(voltage);
Log.v("Log", "getValue" + voltage);
break;
}
}
}
Logcat:

The reason of the error is here:
BTHandler btHandler;
and you are doing this:
btHandler.write(voltage);
but the object is null referenced....
you need to initialize the BTHandler in the oncreate...
or maybe better:
use a service so you can Bind all the activities to that...
PS:
Note that the BTHandler of the MainActivity is not the same as the one declared in the SPA Class... so although that btHandler is constructed and works in MainActivity doesnt mean it will work in other activities/classes