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Android and BLE

I'm working on a project in which I want to receive the data(, separated value"only two values") from BLE server. my first question is I write the code for connection but I din't connect with it. and second how to read this comma separated value. and this comma separated value will come from arduino to BLE server and from BLE server the communication will be done between both. Code is Below.
IDs
#define SERVICE_UUID "ab0828b1-198e-4351-b779-901fa0e0371e"
#define CHARACTERISTIC_UUID_RX "4ac8a682-9736-4e5d-932b-e9b31405049c"
#define CHARACTERISTIC_UUID_TX "0972EF8C-7613-4075-AD52-756F33D4DA91"
code
package com.grng.rthr;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import com.grng.rthr.main.core.viewmodel.MainViewModel;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.Toolbar;
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.grng.rthr.main.BackAwareApplication;
import com.grng.rthr.main.core.viewmodel.MainViewModel;
import com.grng.rthr.main.ui.fragment.atWork.ModeFragment;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.util.Set;
import java.util.UUID;
public class BluetoothActivity extends AppCompatActivity {
// GUI Components
private TextView mBluetoothStatus;
private MainViewModel viewModel;
private TextView mReadBuffer;
private Button mScanBtn;
private Button mOffBtn;
private BluetoothAdapter mBTAdapter;
private Set<BluetoothDevice> mPairedDevices;
private ArrayAdapter<String> mBTArrayAdapter;
private ListView mDevicesListView;
private final String TAG = BluetoothActivity.class.getSimpleName();
private Handler mHandler; // Our main handler that will receive callback notifications
private ConnectedThread mConnectedThread; // bluetooth background worker thread to send and receive data
private BluetoothSocket mBTSocket = null; // bi-directional client-to-client data path
private static final UUID BTMODULEUUID = UUID.fromString("ab0828b1-198e-4351-b779-901fa0e0371e"); // "random" unique identifier
// #defines for identifying shared types between calling functions
private final static int REQUEST_ENABLE_BT = 1; // used to identify adding bluetooth names
private final static int MESSAGE_READ = 2; // used in bluetooth handler to identify message update
private final static int CONNECTING_STATUS = 3; // used in bluetooth handler to identify message status
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth);
// setTitle("Belt Monitoring");
setTitle("Belt Monitoring");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_back_btn);
mBluetoothStatus = (TextView)findViewById(R.id.bluetoothStatus);
mReadBuffer = (TextView) findViewById(R.id.readBuffer);
mScanBtn = (Button)findViewById(R.id.scan);
mOffBtn = (Button)findViewById(R.id.off);
mBTArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
mBTAdapter = BluetoothAdapter.getDefaultAdapter(); // get a handle on the bluetooth radio
mDevicesListView = (ListView)findViewById(R.id.devicesListView);
mDevicesListView.setAdapter(mBTArrayAdapter); // assign model to view
mDevicesListView.setOnItemClickListener(mDeviceClickListener);
bluetoothOn();
// Ask for location permission if not already allowed
if(ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, 1);
mHandler = new Handler(){
public void handleMessage(android.os.Message msg){
if(msg.what == MESSAGE_READ){
String readMessage = null;
try {
readMessage = new String((byte[]) msg.obj, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
mReadBuffer.setText(readMessage);
}
if(msg.what == CONNECTING_STATUS){
if(msg.arg1 == 1)
mBluetoothStatus.setText("Connected to Device: " + (String)(msg.obj));
else
mBluetoothStatus.setText("Connection Failed");
}
}
};
if (mBTArrayAdapter == null) {
// Device does not support Bluetooth
mBluetoothStatus.setText("Status: Bluetooth not found");
Toast.makeText(getApplicationContext(),"Bluetooth device not found!",Toast.LENGTH_SHORT).show();
}
else {
mScanBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
bluetoothScan(v);
}
});
mOffBtn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
bluetoothOff(v);
}
});
}
}
private void bluetoothOn(){
if (!mBTAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
mBluetoothStatus.setText("Bluetooth enabled");
Toast.makeText(getApplicationContext(),"Bluetooth turned on",Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(getApplicationContext(),"Bluetooth is already on", Toast.LENGTH_SHORT).show();
}
}
private void bluetoothScan(View view){
mBTArrayAdapter.clear();
mPairedDevices = mBTAdapter.getBondedDevices();
if(mBTAdapter.isEnabled()) {
// put it's one to the adapter
for (BluetoothDevice device : mPairedDevices)
mBTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
Toast.makeText(getApplicationContext(), "Show Paired Devices", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(getApplicationContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
}
discovering();
}
private void discovering(){
if(mBTAdapter.isDiscovering()){
mBTAdapter.cancelDiscovery();
Toast.makeText(getApplicationContext(),"Discovery stopped",Toast.LENGTH_SHORT).show();
}
else{
if(mBTAdapter.isEnabled()) {
mBTArrayAdapter.clear(); // clear items
mBTAdapter.startDiscovery();
Toast.makeText(getApplicationContext(), "Discovery started", Toast.LENGTH_SHORT).show();
registerReceiver(blReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
else{
Toast.makeText(getApplicationContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
}
}
}
// Enter here after user selects "yes" or "no" to enabling radio
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent Data){
// Check which request we're responding to
if (requestCode == REQUEST_ENABLE_BT) {
// Make sure the request was successful
if (resultCode == RESULT_OK) {
// The user picked a contact.
// The Intent's data Uri identifies which contact was selected.
mBluetoothStatus.setText("Enabled");
}
else
mBluetoothStatus.setText("Disabled");
}
}
private void bluetoothOff(View view){
mBTAdapter.disable(); // turn off
mBluetoothStatus.setText("Bluetooth disabled");
Toast.makeText(getApplicationContext(),"Bluetooth turned Off", Toast.LENGTH_SHORT).show();
}
final BroadcastReceiver blReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(BluetoothDevice.ACTION_FOUND.equals(action)){
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// add the name to the list
mBTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
mBTArrayAdapter.notifyDataSetChanged();
}
}
};
private AdapterView.OnItemClickListener mDeviceClickListener = new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) {
if(!mBTAdapter.isEnabled()) {
Toast.makeText(getBaseContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
return;
}
mBluetoothStatus.setText("Connecting...");
// Get the device MAC address, which is the last 17 chars in the View
String info = ((TextView) v).getText().toString();
final String address = info.substring(info.length() - 17);
final String name = info.substring(0,info.length() - 17);
// Spawn a new thread to avoid blocking the GUI one
new Thread()
{
public void run() {
boolean fail = false;
BluetoothDevice device = mBTAdapter.getRemoteDevice(address);
try {
mBTSocket = createBluetoothSocket(device);
} catch (IOException e) {
fail = true;
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_SHORT).show();
}
// Establish the Bluetooth socket connection.
try {
mBTSocket.connect();
} catch (IOException e) {
try {
fail = true;
mBTSocket.close();
mHandler.obtainMessage(CONNECTING_STATUS, -1, -1)
.sendToTarget();
} catch (IOException e2) {
//insert code to deal with this
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_SHORT).show();
}
}
if(fail == false) {
mConnectedThread = new ConnectedThread(mBTSocket);
mConnectedThread.start();
mHandler.obtainMessage(CONNECTING_STATUS, 1, -1, name)
.sendToTarget();
}
}
}.start();
}
};
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {
try {
final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", UUID.class);
return (BluetoothSocket) m.invoke(device, BTMODULEUUID);
} catch (Exception e) {
Log.e(TAG, "Could not create Insecure RFComm Connection",e);
}
return device.createRfcommSocketToServiceRecord(BTMODULEUUID);
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.available();
if(bytes != 0) {
buffer = new byte[1024];
SystemClock.sleep(100); //pause and wait for rest of data. Adjust this depending on your sending speed.
bytes = mmInStream.available(); // how many bytes are ready to be read?
bytes = mmInStream.read(buffer, 0, bytes); // record how many bytes we actually read
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
.sendToTarget(); // Send the obtained bytes to the UI activity
}
} catch (IOException e) {
e.printStackTrace();
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(String input) {
byte[] bytes = input.getBytes(); //converts entered String into 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) { }
}
}
}

Making a bluetooth service that sends a signal to arduino bluetooth module

So I have been working with arduino for a while and now I've been trying to connect to the blue-tooth module with android studio. I was able to get the blue-tooth to connect but I'm having issues making the blue-tooth connection a service so that it can run even if the app is closed. Whenever I try to get the service to run on my phone, the app crashes as soon as i try to connect to blue-tooth module where as before when it was an activity, it worked perfectly. I've looked at a lot of links and guides on using services and blue-tooth but none of them do exactly what I want.
Below are some code snippets, but here is a link to the entire GitHub project
Blue-tooth activity that I got to work:
package edu.memphis.teamhack.smart_nightlight;
import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.util.Set;
import java.util.UUID;
public class BluetoothActivity extends AppCompatActivity {
// GUI Components
private TextView mBluetoothStatus;
private TextView mReadBuffer;
private Button mScanBtn;
private Button mOffBtn;
private Button mListPairedDevicesBtn;
private Button mDiscoverBtn;
private BluetoothAdapter mBTAdapter;
private Set<BluetoothDevice> mPairedDevices;
private ArrayAdapter<String> mBTArrayAdapter;
private ListView mDevicesListView;
private CheckBox mLED1;
private final String TAG = MainActivity.class.getSimpleName();
private Handler mHandler; // Our main handler that will receive callback notifications
private ConnectedThread mConnectedThread; // bluetooth background worker thread to send and receive data
private BluetoothSocket mBTSocket = null; // bi-directional client-to-client data path
private static final UUID BTMODULEUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // "random" unique identifier
// #defines for identifying shared types between calling functions
private final static int REQUEST_ENABLE_BT = 1; // used to identify adding bluetooth names
private final static int MESSAGE_READ = 2; // used in bluetooth handler to identify message update
private final static int CONNECTING_STATUS = 3; // used in bluetooth handler to identify message status
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth);
mBluetoothStatus = (TextView)findViewById(R.id.bluetoothStatus);
mReadBuffer = (TextView) findViewById(R.id.readBuffer);
mScanBtn = (Button)findViewById(R.id.scan);
mOffBtn = (Button)findViewById(R.id.off);
mDiscoverBtn = (Button)findViewById(R.id.discover);
mListPairedDevicesBtn = (Button)findViewById(R.id.PairedBtn);
mLED1 = (CheckBox)findViewById(R.id.checkboxLED1);
mBTArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
mBTAdapter = BluetoothAdapter.getDefaultAdapter(); // get a handle on the bluetooth radio
mDevicesListView = (ListView)findViewById(R.id.devicesListView);
mDevicesListView.setAdapter(mBTArrayAdapter); // assign model to view
mDevicesListView.setOnItemClickListener(mDeviceClickListener);
// Ask for location permission if not already allowed
if(ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, 1);
mHandler = new Handler(){
public void handleMessage(android.os.Message msg){
if(msg.what == MESSAGE_READ){
String readMessage = null;
try {
readMessage = new String((byte[]) msg.obj, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
mReadBuffer.setText(readMessage);
}
if(msg.what == CONNECTING_STATUS){
if(msg.arg1 == 1)
mBluetoothStatus.setText("Connected to Device: " + (String)(msg.obj));
else
mBluetoothStatus.setText("Connection Failed");
}
}
};
if (mBTArrayAdapter == null) {
// Device does not support Bluetooth
mBluetoothStatus.setText("Status: Bluetooth not found");
Toast.makeText(getApplicationContext(),"Bluetooth device not found!",Toast.LENGTH_SHORT).show();
}
else {
mLED1.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
SharedPreferences settings = getSharedPreferences("MyPref",
Context.MODE_PRIVATE);
Integer myInt = settings.getInt("colorHex", 0);
if(mConnectedThread != null){ //First check to make sure thread created
mConnectedThread.write(myInt.toString());}
}
});
mScanBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
bluetoothOn(v);
}
});
mOffBtn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
bluetoothOff(v);
}
});
mListPairedDevicesBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v){
listPairedDevices(v);
}
});
mDiscoverBtn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
discover(v);
}
});
}
}
private void bluetoothOn(View view){
if (!mBTAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
mBluetoothStatus.setText("Bluetooth enabled");
Toast.makeText(getApplicationContext(),"Bluetooth turned on",Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(getApplicationContext(),"Bluetooth is already on", Toast.LENGTH_SHORT).show();
}
}
// Enter here after user selects "yes" or "no" to enabling radio
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent Data){
// Check which request we're responding to
if (requestCode == REQUEST_ENABLE_BT) {
// Make sure the request was successful
if (resultCode == RESULT_OK) {
// The user picked a contact.
// The Intent's data Uri identifies which contact was selected.
mBluetoothStatus.setText("Enabled");
}
else
mBluetoothStatus.setText("Disabled");
}
}
private void bluetoothOff(View view){
mBTAdapter.disable(); // turn off
mBluetoothStatus.setText("Bluetooth disabled");
Toast.makeText(getApplicationContext(),"Bluetooth turned Off", Toast.LENGTH_SHORT).show();
}
private void discover(View view){
// Check if the device is already discovering
if(mBTAdapter.isDiscovering()){
mBTAdapter.cancelDiscovery();
Toast.makeText(getApplicationContext(),"Discovery stopped",Toast.LENGTH_SHORT).show();
}
else{
if(mBTAdapter.isEnabled()) {
mBTArrayAdapter.clear(); // clear items
mBTAdapter.startDiscovery();
Toast.makeText(getApplicationContext(), "Discovery started", Toast.LENGTH_SHORT).show();
registerReceiver(blReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
else{
Toast.makeText(getApplicationContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
}
}
}
final BroadcastReceiver blReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(BluetoothDevice.ACTION_FOUND.equals(action)){
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// add the name to the list
mBTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
mBTArrayAdapter.notifyDataSetChanged();
}
}
};
private void listPairedDevices(View view){
mPairedDevices = mBTAdapter.getBondedDevices();
if(mBTAdapter.isEnabled()) {
// put it's one to the adapter
for (BluetoothDevice device : mPairedDevices)
mBTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
Toast.makeText(getApplicationContext(), "Show Paired Devices", Toast.LENGTH_SHORT).show();
}
else
Toast.makeText(getApplicationContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
}
private AdapterView.OnItemClickListener mDeviceClickListener = new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) {
if(!mBTAdapter.isEnabled()) {
Toast.makeText(getBaseContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
return;
}
mBluetoothStatus.setText("Connecting...");
// Get the device MAC address, which is the last 17 chars in the View
String info = ((TextView) v).getText().toString();
final String address = info.substring(info.length() - 17);
final String name = info.substring(0,info.length() - 17);
// Spawn a new thread to avoid blocking the GUI one
new Thread()
{
public void run() {
boolean fail = false;
BluetoothDevice device = mBTAdapter.getRemoteDevice(address);
try {
mBTSocket = createBluetoothSocket(device);
} catch (IOException e) {
fail = true;
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_SHORT).show();
}
// Establish the Bluetooth socket connection.
try {
mBTSocket.connect();
} catch (IOException e) {
try {
fail = true;
mBTSocket.close();
mHandler.obtainMessage(CONNECTING_STATUS, -1, -1)
.sendToTarget();
} catch (IOException e2) {
//insert code to deal with this
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_SHORT).show();
}
}
if(fail == false) {
mConnectedThread = new ConnectedThread(mBTSocket);
mConnectedThread.start();
mHandler.obtainMessage(CONNECTING_STATUS, 1, -1, name)
.sendToTarget();
}
}
}.start();
}
};
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {
try {
final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", UUID.class);
return (BluetoothSocket) m.invoke(device, BTMODULEUUID);
} catch (Exception e) {
Log.e(TAG, "Could not create Insecure RFComm Connection",e);
}
return device.createRfcommSocketToServiceRecord(BTMODULEUUID);
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[1024]; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.available();
if(bytes != 0) {
buffer = new byte[1024];
SystemClock.sleep(100); //pause and wait for rest of data. Adjust this depending on your sending speed.
bytes = mmInStream.available(); // how many bytes are ready to be read?
bytes = mmInStream.read(buffer, 0, bytes); // record how many bytes we actually read
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
.sendToTarget(); // Send the obtained bytes to the UI activity
}
} catch (IOException e) {
e.printStackTrace();
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(String input) {
byte[] bytes = input.getBytes(); //converts entered String into 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) { }
}
}
Here is the Bluetooth Service I'm working on:
package edu.memphis.teamhack.smart_nightlight;
import android.app.Service;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Toast;
public class BluetoothCommService extends Service {
// #defines for identifying shared types between calling functions
private final static int REQUEST_ENABLE_BT = 1; // used to identify adding bluetooth names
private BluetoothAdapter mBTAdapter;
private ArrayAdapter<String> mBTArrayAdapter;
public BluetoothCommService() {
}
public void onCreate(Bundle savedInstanceState){
//super.onCreate(savedInstanceState);
mBTAdapter = BluetoothAdapter.getDefaultAdapter(); // get a handle on the bluetooth radio
mBTArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
}
#Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
void bluetoothOn(View view){
if (!mBTAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
//startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
//GUI
//mBluetoothStatus.setText("Bluetooth enabled");
// Toast.makeText(getApplicationContext(),"Bluetooth turned on",Toast.LENGTH_SHORT).show();
}
else{
//Toast.makeText(getApplicationContext(),"Bluetooth is already on", Toast.LENGTH_SHORT).show();
}
}
private void bluetoothOff(View view){
mBTAdapter.disable(); // turn off
//GUI
//mBluetoothStatus.setText("Bluetooth disabled");
//Toast.makeText(getApplicationContext(),"Bluetooth turned Off", Toast.LENGTH_SHORT).show();
}
private void discover(View view){
// Check if the device is already discovering
if(mBTAdapter.isDiscovering()){
mBTAdapter.cancelDiscovery();
Toast.makeText(getApplicationContext(),"Discovery stopped",Toast.LENGTH_SHORT).show();
}
else{
if(mBTAdapter.isEnabled()) {
mBTArrayAdapter.clear(); // clear items
mBTAdapter.startDiscovery();
Toast.makeText(getApplicationContext(), "Discovery started", Toast.LENGTH_SHORT).show();
registerReceiver(blReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
else{
Toast.makeText(getApplicationContext(), "Bluetooth not on", Toast.LENGTH_SHORT).show();
}
}
}
final BroadcastReceiver blReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(BluetoothDevice.ACTION_FOUND.equals(action)){
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// add the name to the list
mBTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
mBTArrayAdapter.notifyDataSetChanged();
}
}
};
}
Feel free to ask any questions.

Try this instructables, i did it by reffering to this tutorial
http://www.instructables.com/id/Android-Bluetooth-Control-LED-Part-2/
for more idea, also refer to
https://www.intorobotics.com/how-to-develop-simple-bluetooth-android-application-to-control-a-robot-remote/

Bluetooth not writing or taking forever to read

import android.annotation.TargetApi;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
#TargetApi(18)
public class MainActivity extends AppCompatActivity{
`int b = 0;
BluetoothAdapter BA = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice device;
BluetoothSocket BS;
BluetoothServerSocket server;
UUID uuid = UUID.fromString("f63b93f5-56e0-47bb-8972-996e34cfb9a8");`
`#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);`
`Intent i = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(i);`
`Accept accept = new Accept();
accept.start();`
Set<BluetoothDevice> devices = BA.getBondedDevices();
for(BluetoothDevice bt : devices) {
try {
if (bt.getName().equals("Overlord")) {
device = BA.getRemoteDevice(bt.getAddress());
BS = device.createRfcommSocketToServiceRecord(uuid);
} else if (bt.getName().equals("Huawei Y5")) {
device = BA.getRemoteDevice(bt.getAddress());
BS = device.createRfcommSocketToServiceRecord(uuid);
}
}catch(IOException IOE){}
}
}
public interface MessageContents{
int MSG_MESSAGE = 0;
}
Handler handler = new Handler(){
public void handleMessage(Message msg) {
TextView tx = (TextView)findViewById(R.id.textView2);
switch(msg.what){
case MessageContents.MSG_MESSAGE:
byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
Log.d("TAG", readMessage);
tx.setText(readMessage);
break;
default:
tx.setText("No text");
}
}
};
class Connect extends Thread{
public void run(){
try {
try {
BS.connect();
Log.d("LOG", " e");
Log.d("LOG", "r" + BS.isConnected());
DataTransfer dataTransfer = new DataTransfer();
dataTransfer.start();
}catch(NullPointerException e){
Log.d("LOG", " meezaan");
}
}catch(IOException e){
Log.d("LOG", "t");
}
}
}
class Accept extends Thread{
public void run() {
try {
while (true) {
server = BA.listenUsingRfcommWithServiceRecord("Secure Connection", uuid);
server.accept();
Log.d("LOG", "accept");
}
}catch(IOException E) {
}
}
}
class DataTransfer extends Thread{
#Override
public void run() {
int d = 1;
InputStream receive = null;
Log.d("LOG", "On");
int numBytes;
byte[] buffer = new byte[1024];
try {
receive = BS.getInputStream();
Log.d("LOG", "pn");
while (BS.isConnected()) {
try {
if (d <= 5) {
Log.d("LOG", "did");
++d;
}
numBytes = receive.read(buffer);
handler.obtainMessage(MessageContents.MSG_MESSAGE, numBytes, -1, buffer).sendToTarget();
} catch (NullPointerException e) {
Log.d("LOG", "error read(null)");
}
}
Log.d("LOG", "pnA");
} catch (IOException IOE) {
Log.d("LOG", "error read(IOE)");
}
}
}
public void onOne(View view){
write("1".getBytes());
}
public void onClick(View view){
Button b1 = (Button) findViewById(R.id.button);
EditText pin = (EditText) findViewById(R.id.editText);
pin.setRawInputType(Configuration.KEYBOARD_QWERTY);
pin.setVisibility(View.VISIBLE);
b1.setVisibility(View.VISIBLE);
}
public void pin (View view) {
Button b1 = (Button)findViewById(R.id.button);
EditText pin = (EditText)findViewById(R.id.editText);
String pin1 = pin.getText().toString();
if (pin1.equals("")) {
Connect connect = new Connect();
connect.run();
pin.setVisibility(View.INVISIBLE);
b1.setVisibility(View.INVISIBLE);
} else {
Toast.makeText(getApplicationContext(), "Wrong Pin!"+pin1, Toast.LENGTH_SHORT).show();
pin.setVisibility(View.INVISIBLE);
b1.setVisibility(View.INVISIBLE);
}
}
public void onTwo(View v){
Toast.makeText(getApplicationContext(), "" + handler.hasMessages(MessageContents.MSG_MESSAGE) + " " + BS.isConnected(), Toast.LENGTH_SHORT).show();
}
public void write(byte[] Byte){
try {
OutputStream transfer = BS.getOutputStream();
try {
transfer.write(Byte);
}catch(NullPointerException e){
Log.d("LOG", "error write(null) " + BS.isConnected());}
}catch (IOException IOE){ Log.d("LOG", "b");
Log.d("LOG", "error write(IOE) " + BS.isConnected());}
}
}`
Hi, this is my code. After writing Bytes[] I don't receive anything on second device. When I remove 'numBytes = receive.read(buffer)' handler would work or display
'no text'
I think receive.read(buffer) waits for an input which means write is a problem or receive.read(buffer) is the problem. Please ignore names, logs with random letters in or device names or unnecessary imports or variables. Thank You :) Sorry I did not have time to indent everything. If you are viewing please put something like don't know.Thank you.

“android.os.NetworkOnMainThreadException” when receiving socket data despite using AsyncTask [duplicate]

This question already has answers here:
NetworkOnMainThreadException [duplicate]
(5 answers)
Closed 7 years ago.
On Being a Duplicate: Please note that I have acknowledged other Q&As (Thread UI) but my case is different as I have tried to use the solution but it doesn't work at all instances (as it works for writing but doesn't for reading.
Updated: I know exactly what is going wrong please read the bold My Question part
I'm trying to make an Android Socket Client that connects to a Java server via WiFi.The final client will send and receive commands and logs as there will be a textbox that user can write SQL commands in it and by hitting a button command will be sent from the app to the Desktop server and show the log in another textbox.
so far I have been trying to use This Answer from another question to make that Client, and adding following lines in the TCP client.
Scanner in = new Scanner(socket.getInputStream());//in doInBackground
//also changed send method a little
public String send(String command)
{
if ( connected ){
out.println(command);
out.flush();
String back = in.nextLine().toString();
return back;
}
return "not Connected";
}
The connection is made successfully and the send method does send the command while server receives it.but the String that server writes back throw the mentioned exception in the title despite the fact that I am using the AsyncTask.
My Question
Why Scanner throws this exception while PrintWriter works correctly ?
Main Activity
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
EditText serverIP, servMsg;
String ip, serverOut;
Button connectBtn;
TcpClient tcpClient;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
serverIP = (EditText) findViewById(R.id.serverIP);
connectBtn = (Button) findViewById(R.id.connectBtn);
servMsg = (EditText) findViewById(R.id.servMsg);
}
public void onConnectBtn(View view){
try{
ip = serverIP.getText().toString();
tcpClient = new TcpClient();
tcpClient.connect(getApplicationContext(), ip, 8082);
serverOut = tcpClient.send("HELLO FROM cat:123");
servMsg.setText(serverOut);
tcpClient.disconnect(getApplicationContext());
}
catch (Exception e){
Toast.makeText(getApplicationContext(),
"Exception on runnning thread: " + e.getMessage().toString(), Toast.LENGTH_LONG).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);
}
}
TCP Client
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Handler;
import android.util.Log;
import android.widget.Toast;
public class TcpClient {
private static final String TAG = TcpClient.class.getSimpleName();
private Socket socket;
private PrintWriter out;
private Scanner in;
private boolean connected;
public TcpClient() {
socket = null;
out = null;
connected = false;
}
public void connect(Context context, String host, int port) {
new ConnectTask(context).execute(host, String.valueOf(port));
}
private class ConnectTask extends AsyncTask<String, Void, Void> {
private Context context;
public ConnectTask(Context context) {
this.context = context;
}
#Override
protected void onPreExecute() {
showToast(context, "Connecting..");
super.onPreExecute();
}
#Override
protected void onPostExecute(Void result) {
if (connected) {
showToast(context, "Connection successful");
}
super.onPostExecute(result);
}
private String host;
private int port;
#Override
protected Void doInBackground(String... params) {
try {
String host = params[0];
int port = Integer.parseInt(params[1]);
socket = new Socket(host, port);
out = new PrintWriter(socket.getOutputStream(), true);
in = new Scanner(socket.getInputStream());
} catch (UnknownHostException e) {
showToast(context, "Don't know about host: " + host + ":" + port);
Log.e(TAG, e.getMessage());
} catch (IOException e) {
showToast(context, "Couldn't get I/O for the connection to: " + host + ":" + port);
Log.e(TAG, e.getMessage());
}
connected = true;
return null;
}
}
public void disconnect(Context context) {
if (connected) {
try {
out.close();
socket.close();
connected = false;
} catch (IOException e) {
showToast(context, "Couldn't get I/O for the connection");
Log.e(TAG, e.getMessage());
}
}
}
/**
* Send command to a Pure Data audio engine.
*/
public String send(String command)
{
if ( connected ){
out.println(command);
out.flush();
String back = in.nextLine().toString();
return back;
}
return "not Connected";
}
private void showToast(final Context context, final String message) {
new Handler(context.getMainLooper()).post(new Runnable() {
#Override
public void run() {
Toast.makeText(context, message, Toast.LENGTH_LONG).show();
}
});
}
}
Also the Layout right now consist of two TextEdits one in which user types IP of the computer(which I checked with correct IPs) and the second one is going to show Server response.

I believe you are not "flushing", which is essentially forcing the buffer to empty out its contents. Please take a look at this working chat server/client code that uses TCP/IP. On a side note, I would recommend not extending ActionBarActivity because it is deprecated (Google says they will move away from it and won't be supporting it soon). Please see 3rd link.
ChatServer.java
ChatClient.java
ActionBar Activity deprecation

Android Bluetooth Service

I made a program which can connect bluetooth to my device and getting byte from my device.
But the program cannot running in the background.
I only want to get byte in the background.
I made another class which extend Service and trying to make my program run.
public class NickyService extends Service {
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent,flags,startId);
//Wrong code
MainActivity a1 = new MainActivity();
return START_NOT_STICKY;
}
}
I have no idea with fixing this.
How do I fix this big problem?
The following codes is right!
It can get byte and connect to device,but cannot running in the background!!
MainActivity.java
package com.example.bluetooth10;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import org.apache.http.util.ByteArrayBuffer;
import android.app.Service;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Vibrator;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
// textview for connection status
ListView pairedListView;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
TextView sensorView0, title_paired_devices;
String paired = "";
Handler bluetoothIn;
private TextView connecting_str;
private TextView textView1;
final int handlerState = 0; // used to identify handler message
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private ByteArrayBuffer baf1 = new ByteArrayBuffer(32);
String path = Environment.getExternalStorageDirectory().toString();
private ConnectedThread mConnectedThread;
private static final UUID BTMODULEUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // SPP UUID service - this should work for most devices
private static String address; // String for MAC address
protected void onHandleIntent(Intent workIntent) {
// Gets data from the incoming Intent
String dataString = workIntent.getDataString();
// Do work here, based on the contents of dataString
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView1 = (TextView) findViewById(R.id.textView1);
title_paired_devices = (TextView) findViewById(R.id.title_paired_devices);
...
bluetoothIn = new Handler() {
public void handleMessage(android.os.Message msg) {
connecting_str.setText("Connection!!");
byte[] readBuf = (byte[]) msg.obj; // obj = buffer from connect thread
for (int i=0; i<msg.arg1; i++) {
baf1.append((byte)readBuf[i]);
if (baf1.length()>1){
String str1 = String.format("%02X",(byte)baf1.byteAt(baf1.length()-2));
String str2 = String.format("%02X",(byte)baf1.byteAt(baf1.length()-1));
if (str1.equals("01") && str2.equals("FF")){
int tmpb = (byte)baf1.byteAt(13);
baf1.clear();
}
}
}
}
int toInt( byte[] bytes ) {
int result = 0;
for (int i=0; i<bytes.length; i++) {
result = ( result << 8 ) - Byte.MIN_VALUE + (int) bytes[i];
}
return result;
}
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get Bluetooth adapter
checkBTState();
}
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException
{
return device.createRfcommSocketToServiceRecord(BTMODULEUUID);
//creates secure outgoing connecetion with BT device using UUID
}
public void onResume() {
super.onResume();
checkBTState();
btAdapter = BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> pairedDevices = btAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);//make title viewable
for (BluetoothDevice device : pairedDevices) {
if (!paired.equals("")) paired = paired + ",";
paired = paired + device.getName() + ";" + device.getAddress();
}
} else {
paired = "no devices paired";
}
String str0[] = paired.split(",");
String str1 = str0[0]; //pairedListView.getItemAtPosition(0).toString(); //Get MAC address from DeviceListActivity
String str2[] = str1.split(";");
address = str2[1]; //Get the MAC address from the DeviceListActivty via EXTRA
BluetoothDevice device = btAdapter.getRemoteDevice(address); //create device and set the MAC address
try {
btSocket = createBluetoothSocket(device);
} catch (IOException e) {
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_LONG).show();
}
try {
btSocket.connect();
} catch (IOException e) {
try {
btSocket.close();
} catch (IOException e2) { }
}
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
}
public void onPause() {
super.onPause();
try {
btSocket.close(); //Don't leave Bluetooth sockets open when leaving activity
} catch (IOException e2) { }
}
private void checkBTState() {
btAdapter = BluetoothAdapter.getDefaultAdapter(); // CHECK THIS OUT THAT IT WORKS!!!
if(btAdapter==null) {
Toast.makeText(getBaseContext(), "Device does not support Bluetooth", Toast.LENGTH_SHORT).show();
finish();
} else {
if (!btAdapter.isEnabled()) {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
// ***********************************************************
// create new class for connect thread
// ***********************************************************
private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;
//creation of the connect thread
public ConnectedThread(BluetoothSocket socket) {
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
//Create I/O streams for connection
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[40]; //The arduino is sending a small amount of data so a large buffer is not needed
int bytes;
// Keep looping to listen for received messages
while (true) {
try {
bytes = mmInStream.read(buffer); //read bytes from input buffer
bluetoothIn.obtainMessage(handlerState, bytes, -1, buffer).sendToTarget(); //Send message to handler
} catch (IOException e) {
break;
}
}
}
}
}