Develop Reference

Arduino to Android: Reading from bluetooth input executes twice when .print is only executed once in arudino

I'm writing a program in android that comminicates with an arduino two ways. When communicating back to the android I'm using .print to write to the serial port back to the android. But what happens is that android registers two messages. If the first message is "message" the first message is "m" and the other is "essage" why is splitting the message?
Arduino code:
#include <SoftwareSerial.h>
int rx = 2;
int tx = 3;
SoftwareSerial bt(tx, rx);
int led1 = 10;
char data = 0;
bool room1on;
void setup() {
bt.begin(9600);
bool room1on = false;
pinMode(led1, OUTPUT);
}
void loop() {
if (bt.available() > 0) {
data = (char)bt.read();
if(data == '1'){
if(room1on){
digitalWrite(led1, LOW);
bt.print("room1;OFF");
}
else if(!room1on){
digitalWrite(led1, HIGH);
bt.print("room1;ON");
}
room1on = !room1on;
}
}
}
android code:
package com.example.beyu.benapp4;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.bluetooth.BluetoothSocket;
import java.io.IOException;
import java.util.Set;
import android.os.Handler;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private final BluetoothAdapter ba = BluetoothAdapter.getDefaultAdapter();
private final static int REQUEST_ENABLE_BT = 1;
private BluetoothDevice btDevice;
BluetoothSocket btSocket;
Handler btHandle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (ba != null) {
if (!ba.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
Set<BluetoothDevice> pairedDevices = ba.getBondedDevices();
// If there are paired devices
if (pairedDevices.size() > 0) {
// Loop through paired devicesUUID.randomUUID()
for (BluetoothDevice device : pairedDevices) {
if(device.getName().equals("HC-06")){
btDevice = device;
try {
btSocket = device.createInsecureRfcommSocketToServiceRecord(btDevice.getUuids()[0].getUuid());
btSocket.connect();
new ConnectedThread(btSocket).start();
}
catch (IOException e) { }
break;
}
}
}
}
btHandle = new Handler() {
public void handleMessage(android.os.Message msg) {
String m = (String) msg.obj;
//TextView tw = (TextView)findViewById(getResources().getIdentifier(textview, "id", getPackageName()));
//if(tw != null)
// tw.setText(message);
}
};
}
public class ConnectedThread extends Thread {
public ConnectedThread(BluetoothSocket socket) {
}
public void run() {
byte[] buffer = new byte[1024];
int bytes;
while (true) {
try {
bytes = btSocket.getInputStream().read(buffer);
String readMessage = new String(buffer, 0, bytes);
btHandle.obtainMessage(0, bytes, -1, readMessage).sendToTarget();
} catch (IOException e) {
break;
}
}
}
}
protected void toogleRoomOne(View view){
try {
btSocket.getOutputStream().write('1');
}
catch (IOException e) {
e.printStackTrace();
}
}
}
When "1" is sent to the ardunio, android response like this:

Your messages come in fragmented. This is quite normal for TCP connections. You have to concatenate them together to get the original message.
For that you have to know the end of the message. One would use a message separater character for that.
You can make it yourself easy to send a newline char after every message string. For instance "lamp1;ON\n". You send a line then.
At receiving side you can wait for a \n to come in but much easier is to read a line with .readLine()

Bluetooth project,when bluetooth is disconnected or out of range

I am trying to program that will display a notification when bluetooth device (arduino uno)disconnected or out of range.
When i testing ,power off the bluetooth device,phone has delay 20s show the notificatoin.
I don't know why,hope somebody help me figure it out.
package com.example.arduinosensors;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Calendar;
import java.util.Timer;
import java.util.TimerTask;
import java.util.UUID;
import android.app.Activity;
import android.app.AlertDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Vibrator;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
Button btnOn, btnOff;
TextView txtArduino, txtString, txtStringLength, sensorView0, sensorView1, sensorView2, sensorView3;
Handler bluetoothIn;
public static final int handlerState = 0,MESSAGE_LOST_CONNECT = 1; //used to identify handler message
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder recDataString = new StringBuilder();
private Vibrator mVibrator;
private ConnectedThread mConnectedThread;
// SPP UUID service - this should work for most devices
private static final UUID BTMODULEUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Insert your bluetooth devices MAC address
private static String address = "20:14:12:03:11:31";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Link the buttons and textViews to respective views
btnOn = (Button) findViewById(R.id.buttonOn);
btnOff = (Button) findViewById(R.id.buttonOff);
txtString = (TextView) findViewById(R.id.txtString);
txtStringLength = (TextView) findViewById(R.id.testView1);
sensorView0 = (TextView) findViewById(R.id.sensorView0);
sensorView1 = (TextView) findViewById(R.id.sensorView1);
sensorView2 = (TextView) findViewById(R.id.sensorView2);
sensorView3 = (TextView) findViewById(R.id.sensorView3);
mVibrator=(Vibrator) getSystemService(VIBRATOR_SERVICE);
bluetoothIn = new Handler() {
public void handleMessage(android.os.Message msg) {
if (msg.what == handlerState) { //if message is what we want
String readMessage = (String) msg.obj; // msg.arg1 = bytes from connect thread
recDataString.append(readMessage); //keep appending to string until ~
int endOfLineIndex = recDataString.indexOf("~"); // determine the end-of-line
if (endOfLineIndex > 0) { // make sure there data before ~
String dataInPrint = recDataString.substring(0, endOfLineIndex); // extract string
txtString.setText("Data Received = " + dataInPrint);
int dataLength = dataInPrint.length(); //get length of data received
txtStringLength.setText("String Length = " + String.valueOf(dataLength));
if (recDataString.charAt(0) == '#') //if it starts with # we know it is what we are looking for
{
String sensor0 = recDataString.substring(1, 5); //get sensor value from string between indices 1-5
String sensor1 = recDataString.substring(6, 10); //same again...
String sensor2 = recDataString.substring(11, 15);
String sensor3 = recDataString.substring(16, 20);
sensorView0.setText(" Sensor 0 Voltage = " + sensor0 + "V"); //update the textviews with sensor values
sensorView1.setText(" Sensor 1 Voltage = " + sensor1 + "V");
sensorView2.setText(" Sensor 2 Voltage = " + sensor2 + "V");
sensorView3.setText(" Sensor 3 Voltage = " + sensor3 + "V");
}
recDataString.delete(0, recDataString.length()); //clear all string data
}
}
if(msg.what == MESSAGE_LOST_CONNECT) { //
//Toast.makeText(getApplicationContext(), "", Toast.LENGTH_LONG).show();
mVibrator.vibrate(new long[]{10, 100, 100, 100}, -1);
new AlertDialog.Builder(MainActivity.this)
.setTitle("bluetooth disconnected")
.setIcon(R.drawable.blue1)
.setMessage("bluetooth out of range")
.setPositiveButton("yes", new
DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogInterface, int i)
{
//finish();
}
})
.setNegativeButton("cancel", new
DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialogInterface, int i)
{
}
})
.show();
}
}
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get Bluetooth adapter
checkBTState();
btnOff.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
mConnectedThread.write("0"); // Send "0" via Bluetooth
Toast.makeText(getBaseContext(), "Turn off LED", Toast.LENGTH_SHORT).show();
}
});
btnOn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
mConnectedThread.write("1"); // Send "1" via Bluetooth
Toast.makeText(getBaseContext(), "Turn on LED", Toast.LENGTH_SHORT).show();
}
});
}
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {
return device.createRfcommSocketToServiceRecord(BTMODULEUUID);
//creates secure outgoing connecetion with BT device using UUID
}
#Override
public void onResume() {
super.onResume();
//Get MAC address from DeviceListActivity via intent
Intent intent = getIntent();
//Get the MAC address from the DeviceListActivty via EXTRA
//address = intent.getStringExtra(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
//create device and set the MAC address
BluetoothDevice device = btAdapter.getRemoteDevice(address);
try {
btSocket = createBluetoothSocket(device);
} catch (IOException e) {
Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_LONG).show();
}
// Establish the Bluetooth socket connection.
try
{
btSocket.connect();
} catch (IOException e) {
try
{
btSocket.close();
} catch (IOException e2)
{
//insert code to deal with this
}
}
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
//I send a character when resuming.beginning transmission to check device is connected
//If it is not an exception will be thrown in the write method and finish() will be called
mConnectedThread.write("x");
}
#Override
public void onPause()
{
super.onPause();
try
{
//Don't leave Bluetooth sockets open when leaving activity
btSocket.close();
} catch (IOException e2) {
//insert code to deal with this
}
}
//Checks that the Android device Bluetooth is available and prompts to be turned on if off
private void checkBTState() {
if(btAdapter==null) {
Toast.makeText(getBaseContext(), "裝置並不支援藍芽", Toast.LENGTH_LONG).show();
} else {
if (btAdapter.isEnabled()) {
} else {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
//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;
}
private void connectionLost() { //斷線通知副程式
// Send a failure message back to the Activity
Message msg = bluetoothIn.obtainMessage(MainActivity.MESSAGE_LOST_CONNECT);
bluetoothIn.sendMessage(msg);
}
public void run() {
byte[] buffer = new byte[256];
int bytes;
// Keep looping to listen for received messages
while (true) {
try {
bytes = mmInStream.read(buffer); //read bytes from input buffer
String readMessage = new String(buffer, 0, bytes);
// Send the obtained bytes to the UI Activity via handler
bluetoothIn.obtainMessage(handlerState, bytes, -1, readMessage).sendToTarget();
} catch (IOException e) {
connectionLost();
break;
}
}
}
//write method
public void write(String input) {
byte[] msgBuffer = input.getBytes(); //converts entered String into bytes
try {
mmOutStream.write(msgBuffer); //write bytes over BT connection via outstream
} catch (IOException e) {
//if you cannot write, close the application
Toast.makeText(getBaseContext(), "連線失敗", Toast.LENGTH_LONG).show();
finish();
}
}
}
}

Can't Get Android Native Access

Tried using native access to implement a bluetooth functionality in android but on starting the app on a device it seems the native access variable is null. Need help in figuring out why it happened and how to solve it. Thanks
These are my build hints
An example of usage in StateMachine class
BTNative nativeBT = (BTNative)NativeLookup.create(BTNative.class);
#Override
protected void onMain_ScanButtonAction(Component c, ActionEvent event) {
super.onMain_ScanButtonAction(c, event);
try {
if (nativeBT != null && nativeBT.isSupported()) {
try {
nativeBT.findBT();
nativeBT.openBT();
} catch (Throwable t) {
Dialog.show("Error", "Exception during findBT and openBT access: " + t, "OK", null);
}
}else{
Dialog.show("Error", "Can't get native access", "OK", null);
}
} catch (Throwable t) {
Dialog.show("Error", "Exception during native access: " + t, "OK", null);
}
}
NativeImpl
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import android.widget.Toast;
public class BTNativeImpl{
//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;
public void closeBT() {
try {
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
//this will send text data to be printed by the bluetooth printer
public void sendData(String param){
try {
// the text typed by the user
param += "\n";
mmOutputStream.write(param.getBytes());
// tell the user data were sent
} catch (Exception e) {
e.printStackTrace();
}
}
//this will find a bluetooth printer device
public void findBT() {
try {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "No bluetooth adapter available", Toast.LENGTH_LONG).show();
}
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
com.codename1.impl.android.AndroidNativeUtil.getActivity().startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
if (device.getName().equals("BlueTooth Printer")) {
mmDevice = device;
break;
}
}
}
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "Bluetooth device found.", Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
}
public void openBT() {
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();
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), "Bluetooth Opened", Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
}
public 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() {
Toast.makeText(com.codename1.impl.android.AndroidNativeUtil.getActivity(), data, Toast.LENGTH_LONG).show();
}
});
} else {
readBuffer[readBufferPosition++] = b;
}
}
}
} catch (IOException ex) {
stopWorker = true;
}
}
}
});
workerThread.start();
} catch (Exception e) {
e.printStackTrace();
}
}
public boolean isSupported() {
return true;
}
}

You likely also need BLUETOOTH_ADMIN permission. I'm not sure if that is the only issue, but definitely would cause problems.
From Android's developer guide:
https://developer.android.com/guide/topics/connectivity/bluetooth.html#Permissions
You also made a big mistake in changing the inheritance of the impl class to derive Activity!
You need to create a separate activity class and register it separately as we create the impl class and Android creates the activity class and both are different. I suggest looking at other cn1libs most of which are open source to see how this was done. I also suggest connecting your device with a cable and viewing output in ddms to track issues.

I am building a bluetooth app for communating another bluetooth device. I am able to scan and get list of available devices

package com.ubitech.tokencallingsystem;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.UUID;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import android.widget.ToggleButton;
public class BluetoothActivity extends Activity{
private final static UUID uuid = UUID.fromString("38bf8160-61ce-11e5-a837-0800200c9a66");
private BluetoothAdapter bluetoothAdapter;
private ToggleButton toggleBtn;
private Button scanBtn;
private ListView listView;
#SuppressWarnings("rawtypes")
private ArrayAdapter adapter;
private static final int ENABLE_BT_REQUEST_CODE = 1;
#SuppressWarnings("rawtypes")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.bluetooth_activity);
toggleBtn = (ToggleButton) findViewById(R.id.toggleButton);
scanBtn = (Button) findViewById(R.id.scan);
listView = (ListView) findViewById(R.id.listView);
adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1);
listView.setAdapter(adapter);
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String itemValue = (String) listView.getItemAtPosition(position);
String MAC = itemValue.substring(itemValue.length() - 17);
Toast.makeText(getApplicationContext(), itemValue+"="+MAC, Toast.LENGTH_SHORT).show();
BluetoothDevice bluetoothDevice = bluetoothAdapter.getRemoteDevice(MAC);
// Initiate a connection request in a separate thread
ConnectingThread t = new ConnectingThread(bluetoothDevice);
t.start();
AcceptThread th = new AcceptThread();
th.start();
System.out.println("In itemonclick listner");
}
});
}
public void onToggleClicked(View view){
//adapter.clear();
if (bluetoothAdapter == null) {
Toast.makeText(getApplicationContext(), "Oops! Bluetooth not supported.", Toast.LENGTH_SHORT).show();
} else {
if(toggleBtn.isChecked()){
scanDevices(view);
} else{
Toast.makeText(getApplicationContext(), "Turning off bluetooth..", Toast.LENGTH_SHORT).show();
adapter.clear();
bluetoothAdapter.disable();
}
}
}
public void scanDevices(View view){
adapter.clear();
if(!bluetoothAdapter.isEnabled()){
Toast.makeText(getApplicationContext(), "Turning on bluetooth..", Toast.LENGTH_SHORT).show();
Intent enableBluetoothIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetoothIntent, ENABLE_BT_REQUEST_CODE);
discoverDevices();
}else{
/* Toast.makeText(getApplicationContext(), "Bluetooth has already been enabled." +
"\n" + "Scanning for available nearby bluetooth devices..",
Toast.LENGTH_SHORT).show();*/
discoverDevices();
}
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == ENABLE_BT_REQUEST_CODE) {
if (resultCode == Activity.RESULT_OK) {
// Toast.makeText(getApplicationContext(), "Bluetooth is now enabled.", Toast.LENGTH_SHORT).show();
discoverDevices();
} else {
// Toast.makeText(getApplicationContext(), "Bluetooth is not enabled.",Toast.LENGTH_SHORT).show();
toggleBtn.setChecked(false);
}
}
}
protected void discoverDevices(){
if (bluetoothAdapter.startDiscovery()) {
Toast.makeText(getApplicationContext(), "Scanning for available nearby bluetooth devices..", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplicationContext(), "Scanning failed to start.", Toast.LENGTH_SHORT).show();
}
}
private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// Whenever a remote Bluetooth device is found
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// Add the name and address to an array adapter to show in a ListView
adapter.add(bluetoothDevice.getName() + "\n"
+ bluetoothDevice.getAddress());
}
if (BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {
final int state = intent.getIntExtra(BluetoothDevice.EXTRA_BOND_STATE, BluetoothDevice.ERROR);
final int prevState = intent.getIntExtra(BluetoothDevice.EXTRA_PREVIOUS_BOND_STATE, BluetoothDevice.ERROR);
if (state == BluetoothDevice.BOND_BONDED && prevState == BluetoothDevice.BOND_BONDING) {
Toast.makeText(getApplicationContext(), "Paired.", Toast.LENGTH_SHORT).show();
} else if (state == BluetoothDevice.BOND_NONE && prevState == BluetoothDevice.BOND_BONDED){
Toast.makeText(getApplicationContext(), "UnPaired.", Toast.LENGTH_SHORT).show();
}
}
}
};
#Override
protected void onResume() {
super.onResume();
// Register the BroadcastReceiver for ACTION_FOUND
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(broadcastReceiver, filter);
}
#Override
protected void onPause() {
super.onPause();
this.unregisterReceiver(broadcastReceiver);
}
private class ConnectingThread extends Thread {
private final BluetoothSocket bluetoothSocket;
private final BluetoothDevice bluetoothDevice;
public ConnectingThread(BluetoothDevice device) {
BluetoothSocket temp = null;
bluetoothDevice = device;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try {
System.out.println("1");
temp = bluetoothDevice.createRfcommSocketToServiceRecord(uuid);
System.out.println("2");
} catch (IOException e) {
System.out.println("In catch exception connecting bt device");
e.printStackTrace();
}
System.out.println("3");
bluetoothSocket = temp;
}
public void run() {
// Cancel discovery as it will slow down the connection
System.out.println("4");
bluetoothAdapter.cancelDiscovery();
try {
// This will block until it succeeds in connecting to the device
// through the bluetoothSocket or throws an exception
System.out.println("5");
if(bluetoothSocket!=null){
bluetoothSocket.connect();
}
/*InputStream inputStream = bluetoothSocket.getInputStream();
OutputStream outputStream = bluetoothSocket.getOutputStream();
outputStream.write(new byte[] { (byte) 0xa0, 0, 7, 16, 0, 4, 0 });*/
Log.e("","Connected");
} catch (IOException connectException) {
System.out.println("In connection exception thread");
connectException.printStackTrace();
try {
System.out.println("6");
bluetoothSocket.close();
System.out.println("7");
} catch (IOException closeException) {
System.out.println("in connection close exception");
closeException.printStackTrace();
}
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally {
if (bluetoothSocket != null) {
try {
Log.d("TCS", ">>Client Close");
bluetoothSocket.close();
finish();
return ;
} catch (IOException e) {
Log.e("EF-BTBee", "", e);
}
}
}
// Code to manage the connection in a separate thread
// manageBluetoothConnection(bluetoothSocket);
}
}
private class AcceptThread extends Thread {
private final BluetoothServerSocket mmServerSocket;
public AcceptThread() {
// Use a temporary object that is later assigned to mmServerSocket,
// because mmServerSocket is final
BluetoothServerSocket tmp = null;
try {
// MY_UUID is the app's UUID string, also used by the client code
tmp = bluetoothAdapter.listenUsingRfcommWithServiceRecord("tcs", uuid);
} catch (IOException e) { }
mmServerSocket = tmp;
}
public void run() {
BluetoothSocket socket = null;
// Keep listening until exception occurs or a socket is returned
while (true) {
try {
socket = mmServerSocket.accept();
} catch (IOException e) {
break;
}
// If a connection was accepted
if (socket != null) {
// Do work to manage the connection (in a separate thread)
//manageConnectedSocket(socket);
try {
mmServerSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
}
}
/** Will cancel the listening socket, and cause the thread to finish */
public void cancel() {
try {
mmServerSocket.close();
} catch (IOException e) { }
}
}
}
This is my activity file. from where i am trying to connect another android device. But when trying to connect nothing happens. Just getting a warning getBluetoothService() called with no BluetoothManagerCallback.

Android sample bluetooth code to send a simple string via bluetooth

I want to send a simple string data such as 'a' from an android device to other one via bluetooth. I looked sample bluetooth code in android sdk but it is so complex for me. I cannot understand how I can send only specific data when I press a button. How can I solve this problem?

private OutputStream outputStream;
private InputStream inStream;
private void init() throws IOException {
BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();
if (blueAdapter != null) {
if (blueAdapter.isEnabled()) {
Set<BluetoothDevice> bondedDevices = blueAdapter.getBondedDevices();
if(bondedDevices.size() > 0) {
Object[] devices = (Object []) bondedDevices.toArray();
BluetoothDevice device = (BluetoothDevice) devices[position];
ParcelUuid[] uuids = device.getUuids();
BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuids[0].getUuid());
socket.connect();
outputStream = socket.getOutputStream();
inStream = socket.getInputStream();
}
Log.e("error", "No appropriate paired devices.");
} else {
Log.e("error", "Bluetooth is disabled.");
}
}
}
public void write(String s) throws IOException {
outputStream.write(s.getBytes());
}
public void run() {
final int BUFFER_SIZE = 1024;
byte[] buffer = new byte[BUFFER_SIZE];
int bytes = 0;
int b = BUFFER_SIZE;
while (true) {
try {
bytes = inStream.read(buffer, bytes, BUFFER_SIZE - bytes);
} catch (IOException e) {
e.printStackTrace();
}
}
}

I made the following code so that even beginners can understand. Just copy the code and read comments. Note that message to be send is declared as a global variable which you can change just before sending the message. General changes can be done in Handler function.
multiplayerConnect.java
import android.annotation.SuppressLint;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Set;
import java.util.UUID;
public class multiplayerConnect extends AppCompatActivity {
public static final int REQUEST_ENABLE_BT=1;
ListView lv_paired_devices;
Set<BluetoothDevice> set_pairedDevices;
ArrayAdapter adapter_paired_devices;
BluetoothAdapter bluetoothAdapter;
public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
public static final int MESSAGE_READ=0;
public static final int MESSAGE_WRITE=1;
public static final int CONNECTING=2;
public static final int CONNECTED=3;
public static final int NO_SOCKET_FOUND=4;
String bluetooth_message="00";
#SuppressLint("HandlerLeak")
Handler mHandler=new Handler()
{
#Override
public void handleMessage(Message msg_type) {
super.handleMessage(msg_type);
switch (msg_type.what){
case MESSAGE_READ:
byte[] readbuf=(byte[])msg_type.obj;
String string_recieved=new String(readbuf);
//do some task based on recieved string
break;
case MESSAGE_WRITE:
if(msg_type.obj!=null){
ConnectedThread connectedThread=new ConnectedThread((BluetoothSocket)msg_type.obj);
connectedThread.write(bluetooth_message.getBytes());
}
break;
case CONNECTED:
Toast.makeText(getApplicationContext(),"Connected",Toast.LENGTH_SHORT).show();
break;
case CONNECTING:
Toast.makeText(getApplicationContext(),"Connecting...",Toast.LENGTH_SHORT).show();
break;
case NO_SOCKET_FOUND:
Toast.makeText(getApplicationContext(),"No socket found",Toast.LENGTH_SHORT).show();
break;
}
}
};
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.multiplayer_bluetooth);
initialize_layout();
initialize_bluetooth();
start_accepting_connection();
initialize_clicks();
}
public void start_accepting_connection()
{
//call this on button click as suited by you
AcceptThread acceptThread = new AcceptThread();
acceptThread.start();
Toast.makeText(getApplicationContext(),"accepting",Toast.LENGTH_SHORT).show();
}
public void initialize_clicks()
{
lv_paired_devices.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
Object[] objects = set_pairedDevices.toArray();
BluetoothDevice device = (BluetoothDevice) objects[position];
ConnectThread connectThread = new ConnectThread(device);
connectThread.start();
Toast.makeText(getApplicationContext(),"device choosen "+device.getName(),Toast.LENGTH_SHORT).show();
}
});
}
public void initialize_layout()
{
lv_paired_devices = (ListView)findViewById(R.id.lv_paired_devices);
adapter_paired_devices = new ArrayAdapter(getApplicationContext(),R.layout.support_simple_spinner_dropdown_item);
lv_paired_devices.setAdapter(adapter_paired_devices);
}
public void initialize_bluetooth()
{
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null) {
// Device doesn't support Bluetooth
Toast.makeText(getApplicationContext(),"Your Device doesn't support bluetooth. you can play as Single player",Toast.LENGTH_SHORT).show();
finish();
}
//Add these permisions before
// <uses-permission android:name="android.permission.BLUETOOTH" />
// <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
// <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
// <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
if (!bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
else {
set_pairedDevices = bluetoothAdapter.getBondedDevices();
if (set_pairedDevices.size() > 0) {
for (BluetoothDevice device : set_pairedDevices) {
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
adapter_paired_devices.add(device.getName() + "\n" + device.getAddress());
}
}
}
}
public class AcceptThread extends Thread
{
private final BluetoothServerSocket serverSocket;
public AcceptThread() {
BluetoothServerSocket tmp = null;
try {
// MY_UUID is the app's UUID string, also used by the client code
tmp = bluetoothAdapter.listenUsingRfcommWithServiceRecord("NAME",MY_UUID);
} catch (IOException e) { }
serverSocket = tmp;
}
public void run() {
BluetoothSocket socket = null;
// Keep listening until exception occurs or a socket is returned
while (true) {
try {
socket = serverSocket.accept();
} catch (IOException e) {
break;
}
// If a connection was accepted
if (socket != null)
{
// Do work to manage the connection (in a separate thread)
mHandler.obtainMessage(CONNECTED).sendToTarget();
}
}
}
}
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
// Use a temporary object that is later assigned to mmSocket,
// because mmSocket is final
BluetoothSocket tmp = null;
mmDevice = device;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try {
// MY_UUID is the app's UUID string, also used by the server code
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) { }
mmSocket = tmp;
}
public void run() {
// Cancel discovery because it will slow down the connection
bluetoothAdapter.cancelDiscovery();
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mHandler.obtainMessage(CONNECTING).sendToTarget();
mmSocket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
try {
mmSocket.close();
} catch (IOException closeException) { }
return;
}
// Do work to manage the connection (in a separate thread)
// bluetooth_message = "Initial message"
// mHandler.obtainMessage(MESSAGE_WRITE,mmSocket).sendToTarget();
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[2]; // 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.read(buffer);
// Send the obtained bytes to the UI activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer).sendToTarget();
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
} catch (IOException e) { }
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
}
multiplayer_bluetooth.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Challenge player"/>
<ListView
android:id="#+id/lv_paired_devices"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
</ListView>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Make sure Device is paired"/>
</LinearLayout>