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change text color with spannable

In the below code which is for bluetooth messaging with arduino i am trying to change color on some static strings.
1.On the start button listener i have a message"Connection opened" which i am changing color using the xml file and creating there a string with specific color. This method works only there.
2. i tried another method with spannable string on the send button listener but is not working at all the message comes in black.
what i want to to do is that when i send a message on my textview i see the "send data: "+ string(msg i send) and i want this send data to be red for examle and the same for the receive one.
What i tried untill now is on the code.If there is any idea to try i will be grateful.
public class MainActivity extends Activity {
private final UUID PORT_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");//Serial Port Service ID
private BluetoothDevice 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);
startButton = findViewById(R.id.buttonStart);
sendButton = findViewById(R.id.buttonSend);
clearButton = findViewById(R.id.buttonClear);
stopButton = findViewById(R.id.buttonStop);
editText = findViewById(R.id.editText);
textView = findViewById(R.id.textView);
textView.setMovementMethod(new ScrollingMovementMethod());
setUiEnabled(false);
startButton.setOnClickListener(v -> {
if(BTinit())
{
if(BTconnect())
{
setUiEnabled(true);
deviceConnected=true;
beginListenForData();
//textView.append("Connection Opened!");
String greenString = getResources().getString(R.string.Connection_Opened);
textView.append(Html.fromHtml(greenString));
}
}
});
sendButton.setOnClickListener(v -> {
String t = "Send Data: ";
SpannableString spannableString = new SpannableString(t);
ForegroundColorSpan green = new ForegroundColorSpan(getResources().getColor(R.color.private_green));
spannableString.setSpan(green, 0, 9, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
String string = editText.getText().toString();
String str = string.concat("\n");
try {
outputStream.write(str.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
textView.append(spannableString + str);
});
stopButton.setOnClickListener(v -> {
try {
stopThread = true;
outputStream.close();
inputStream.close();
socket.close();
setUiEnabled(false);
deviceConnected=false;
textView.append("Connection Closed!");
}catch (IOException e){
e.printStackTrace();
}
});
clearButton.setOnClickListener(v -> textView.setText(""));
}
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 !=null)
{
Intent enableAdapter = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableAdapter, 0);
}
assert bluetoothAdapter != null;
Set<BluetoothDevice> bondedDevices = bluetoothAdapter.getBondedDevices();
if(bondedDevices.isEmpty())
{
Toast.makeText(getApplicationContext(),"Please Pair the Device first",Toast.LENGTH_SHORT).show();
}
else
{
for (BluetoothDevice iterator : bondedDevices)
{
//private final String DEVICE_NAME="ArduinoBT";
String DEVICE_ADDRESS = "98:DA:C0:00:2C:E2";
if(iterator.getAddress().equals(DEVICE_ADDRESS))
{
device=iterator;
found=true;
break;
}
}
}
return found;
}
public boolean BTconnect()
{
boolean connected=true;
try {
socket = device.createRfcommSocketToServiceRecord(PORT_UUID);
socket.connect();
} catch (IOException e) {
e.printStackTrace();
connected=false;
}
if(connected)
{
try {
outputStream=socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
try {
inputStream=socket.getInputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
return connected;
}
void beginListenForData()
{
final Handler handler = new Handler();
stopThread = false;
buffer = new byte[1024];
Thread thread = new Thread(() -> {
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, StandardCharsets.UTF_8);
handler.post(() -> textView.append("Receive data: " + string));
}
}
catch (IOException ex)
{
stopThread = true;
}
}
});
thread.start();
}
}

Try like this;
Spannable text = new SpannableString("Send Data:");
text.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.private_green)), 0, 9, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

Cannot send and receive any data from bluetooth

I have an simple sender/receiver android app based on bluetooth. Connection between two phone is succesfully created. But data is not sending and receiving.
Code what I tried :
public class MainActivity extends Activity
{
TextView myLabel;
EditText myTextbox;
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
volatile boolean stopWorker;
void findBT()
{
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null)
{
myLabel.setText("No bluetooth adapter available");
}
if(!mBluetoothAdapter.isEnabled())
{
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
String deviceName = device.getName();
deviceName=deviceName.replaceAll("[^A-Za-z]+", "");
//String deviceHardwareAddress = device.getAddress(); // MAC address
Log.i("## name : ",deviceName+" ");
if(deviceName.equals("GalaxyTabAwithSPen")) {
mmDevice = device;
break;
}
}
}
// tel GalaxyTabAwithSPen
// tablet GhhBbbGalaxyS
}
void openBT()
{
if(mmDevice==null)
Log.i("test","notnull");
ParcelUuid list[] = mmDevice.getUuids();
for(ParcelUuid x: list){
System.out.println(x.toString());
}
Log.i("size :"+list.length," "+list[1].toString());
UUID uuid = UUID.fromString(list[1].toString()); //Standard SerialPortService ID
//UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
try {
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
myLabel.setText("Bluetooth Opened");
}
catch (Exception ex){
Log.i("IO ex : ", ex.getMessage());
}
}
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];
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)
{
Log.i("IO ex read " ,ex.getMessage());
stopWorker = true;
}
}
}
});
workerThread.start();
}
void sendData() throws IOException
{
String msg = myTextbox.getText().toString();
msg += "\n";
mmOutputStream.write(msg.getBytes());
myLabel.setText("Data Sent");
}
When I click open both tablet and mobile phone, myLabel text changed to "Blueetooth Opened" succesfully.
But when I try to send text to phone from tablet or to table from phone, nothing sended. Data listener is working. mmInputStream.available() always returns 0.
Some log details :
D/BluetoothUtils: isSocketAllowedBySecurityPolicy start : device null
W/BluetoothAdapter: getBluetoothService() called with no BluetoothManagerCallback
D/BluetoothSocket: connect(), SocketState: INIT, mPfd: {ParcelFileDescriptor: FileDescriptor[49]}

Bluetooth printer is not printing data after data is send successfully from android app

Please Help. I am developing a simple bluetooth printer app where I want to print the data entered by user.My code is working properly but printer is not printing the data.
Currently I am using MTP -U- 85 bluetooth printer.
When I send the data from my app the printer color is changing from green to blue color.Also when I connect and disconnect the bluetooth the color is changing between green and blue,blue and green. All things are working correctly but data is not getting printed.
I will give my codes
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
// will show the statuses like bluetooth open, close or data sent
TextView myLabel;
// will enable user to enter any text to be printed
EditText myTextbox;
// android built in classes for bluetooth operations
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
// needed for communication to bluetooth device / network
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
volatile boolean stopWorker;
Button openButton ;
Button sendButton ;
Button closeButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
// we are going to have three buttons for specific functions
openButton = findViewById(R.id.open);
sendButton = findViewById(R.id.send);
closeButton = findViewById(R.id.close);
// text label and input box
myLabel = (TextView) findViewById(R.id.label);
myTextbox = (EditText) findViewById(R.id.entry);
openButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
findBT();
openBT();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
catch(Exception e)
{
e.printStackTrace();
}
// send data typed by the user to be printed
sendButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
sendData();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
// close bluetooth connection
closeButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
closeBT();
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
private void closeBT() throws IOException{
try {
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
myLabel.setText("Bluetooth Closed");
} catch (Exception e) {
e.printStackTrace();
}
}
// this will send text data to be printed by the bluetooth printer
void sendData() throws IOException {
try {
// if(mmOutputStream==null) {
// the text typed by the user
EditText myTextbox = (EditText) findViewById(R.id.entry);
String msg = myTextbox.getText().toString();
msg += "\n";
mmOutputStream = mmSocket.getOutputStream();
mmOutputStream.write(msg.getBytes());
// tell the user data were sent
myLabel.setText("Data sent.");
// }
} catch (Exception e) {
e.printStackTrace();
}
}
// tries to open a connection to the bluetooth printer device
void openBT() throws IOException {
try {
// Standard SerialPortService ID
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
myLabel.setText("Bluetooth Opened");
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* after opening a connection to bluetooth printer device,
* we have to listen and check if a data were sent to be printed.
*/
void beginListenForData()
{
try {
final Handler handler = new Handler();
// this is the ASCII code for a newline character
final byte delimiter = 10;
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];
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
);
// specify US-ASCII encoding
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
// tell the user data were sent to bluetooth printer device
handler.post(new Runnable() {
public void run() {
myLabel.setText(data);
}
});
} else {
readBuffer[readBufferPosition++] = b;
}
}
}
} catch (IOException ex) {
stopWorker = true;
}
}
}
});
workerThread.start();
} catch (Exception e) {
e.printStackTrace();
}
}
private void findBT() {
try {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null) {
myLabel.setText("No bluetooth adapter available");
}
if(!mBluetoothAdapter.isEnabled()) {
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
// RPP300 is the name of the bluetooth printer device
// we got this name from the list of paired devices
if (device.getAddress().equals("DC:1D:30:35:3E:64")) {
mmDevice = device;
break;
}
}
}
myLabel.setText("Bluetooth device found.");
}catch(Exception e){
e.printStackTrace();
}
}
}

void sendData() throws IOException {
try {
if(mmOutputStream==null) {
EditText myTextbox = (EditText) findViewById(R.id.entry);
String msg = myTextbox.getText().toString();
msg += "\n";
mmOutputStream = mmSocket.getOutputStream();
mmOutputStream.write(msg.getBytes());
Thread.sleep(100); // add this line
myLabel.setText("Data sent.");
}
} catch (Exception e) {
e.printStackTrace();
}
}
please also do not forget to check if message is null or not and debug the code

Thanks
Finally its done..
final String finalBILL = BILL;
Thread t = new Thread() {
public void run() {
try {
// This is printer specific code you can comment ==== > Start
mmOutputStream.write(finalBILL.getBytes());
Thread.sleep(100);
mmOutputStream.write(0x1D);
mmOutputStream.write(86);
mmOutputStream.write(48);
mmOutputStream.write(0);
// Clode BT
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
} catch (Exception e) {
Log.e("MainActivity", "Exe ", e);
}
}
};
t.start();

hc-05 display incoming data in TextVieww

I've searched all the topics on stack and Im still stuck with it.
What I m try to do is first display incoming data via bluetooth from microcontroler to TextView strDlugosc and strLenght.
Next step after that will be seperate all the data into Temperature and Voltage TextViews.
I dont know whats going on with it that it dont displaying it...
Please help me
//buttony
Button b_Onled1, b_Onled2, b_Offled1, b_Offled2;
TextView temp_1, temp_2, nap_1, nap_2, strLenght, strDlugosc;
String address = null;
private ProgressDialog progress;
BluetoothAdapter Bta = null;
BluetoothSocket btSocket = null;
private boolean isBtConnected = false;
final int handlerState = 0;
protected static final int SUCCESS_CONNECT = 0;
protected static final int MESSAGE_READ = 1;
//SPP UUID
static final UUID mojeUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_kontrola__led);
Intent newint = getIntent();
address = newint.getStringExtra(MainActivity.EXTRA_ADDRESS);
//wywolanie
b_Onled1 = (Button) findViewById(R.id.b_Onled1);
b_Onled2 = (Button) findViewById(R.id.b_Onled2);
b_Offled1 = (Button) findViewById(R.id.b_Offled1);
b_Offled2 = (Button) findViewById(R.id.b_Offled2);
temp_1 = (TextView) findViewById(R.id.temp_1);
temp_2 = (TextView) findViewById(R.id.temp_2);
nap_1 = (TextView) findViewById(R.id.nap_1);
nap_2 = (TextView) findViewById(R.id.nap_2);
strLenght = (TextView) findViewById(R.id.strLenght);
strDlugosc = (TextView) findViewById(R.id.strDlugosc);
//wywolaj klase by polaczyc
new PolaczBT().execute();
//KOMENDY ONCLICK
b_Onled1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
wlaczLED1();
}
});
b_Onled2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
wlaczLED2();
}
});
b_Offled1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
wylaczLED1();
}
});
b_Offled2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
wylaczLED2();
}
});
}
Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_READ:
ConnectThread connectthread = new ConnectThread(btSocket);
connectthread.start();
final byte[] readBuf = (byte[]) msg.obj;
final String readMessage = new String(readBuf, 0, msg.arg1);
strLenght.setText(readMessage);
break;
}
super.handleMessage(msg);
}
};
private void Disconnect() {
if (btSocket != null) //jezeli socket jest zajety
{
try {
btSocket.close(); //przerwij polaczenie
} catch (IOException e) {
msg("ERROR");
}
}
finish(); // powraca do pierwszego layuoutu
}
private void wylaczLED1() {
if (btSocket != null) {
try {
btSocket.getOutputStream().write("01D0$".toString().getBytes());
} catch (IOException e) {
msg("ERROR");
}
}
}
private void wylaczLED2() {
if (btSocket != null) {
try {
btSocket.getOutputStream().write("02D0$".toString().getBytes());
} catch (IOException e) {
msg("ERROR");
}
}
}
private void wlaczLED1() {
if (btSocket != null) {
try {
btSocket.getOutputStream().write("01D1$".toString().getBytes());
} catch (IOException e) {
msg("ERROR");
}
}
}
private void wlaczLED2() {
if (btSocket != null) {
try {
btSocket.getOutputStream().write("02D1$".toString().getBytes());
} catch (IOException e) {
msg("ERROR");
}
}
}
//************************************************************************
//metoda do przywolywania TOAST*******************************************
//************************************************************************
private void msg(String s) {
Toast.makeText(getApplicationContext(), s, Toast.LENGTH_LONG).show();
}
//*************************************************************************
//POLACZENIE BLUETOOTH*****************************************************
//*************************************************************************
private class PolaczBT extends AsyncTask<Void, Void, Void> {
private boolean ConnectSuccess = true;
#Override
protected void onPreExecute() {
progress = ProgressDialog.show(Kontrola_Led.this, "Laczenie...", "Prosze czekaj!");
}
#Override
protected Void doInBackground(Void... devices) {
try {
if (btSocket == null || !isBtConnected) {
Bta = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice dyspozycyjnosc = Bta.getRemoteDevice(address);
btSocket = dyspozycyjnosc.createInsecureRfcommSocketToServiceRecord(mojeUUID);
BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
btSocket.connect();
}
} catch (IOException e) {
ConnectSuccess = false;
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (!ConnectSuccess) {
msg("Blad polaczenia. Czy SPP BLUETOOTH dziala? Ponow probe. ");
finish();
} else {
msg("Connected.");
isBtConnected = true;
}
progress.dismiss();
}
}
StringBuilder sb = new StringBuilder();
class ConnectThread extends Thread {
final BluetoothSocket mmSocket;
final InputStream mmInStream;
final OutputStream mmOutStream;
public ConnectThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[128];
int bytes;
while (true) {
try {
bytes = mmInStream.read(buffer);
String strIncom = new String(buffer, 0, bytes);
sb.append(strIncom);
int endOfLineIndex = sb.indexOf("\r\n");
if (endOfLineIndex > 0){
String sbprint = sb.substring(0, endOfLineIndex);
strDlugosc.setText(sbprint);
}
mHandler.obtainMessage(Kontrola_Led.MESSAGE_READ, bytes, -1, buffer).sendToTarget();
} catch (IOException e) {
break;
}
}
}
}
}

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