Bluetooth connection in Android > 4.1.2

Bluetooth connection in Android > 4.1.2

I wrote the following activity to connect my Nexus 7 with Arduino, to
simply exchange 0 and 1 to switch on and off a led. I took example from
here:
http://developer.android.com/guide/topics/connectivity/bluetooth.html#ManagingAConnection
and also recalled here: How to connect with paired Bluetooth device
programmatic in Android?
but it almost never connects or if it connects does not display UI. Almost
all the time the app crashes when paused or resumed.
I'm sure there is something wrong in how threads are written, but cannot
understand where.
package com.example.bluetooth3;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;
import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
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 {
private static final String TAG = "bluetooth2";
Button btnOn, btnOff;
TextView txtArduino;
Handler h;
final int receivedMessage = 1; // Status for Handler
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder sb = new StringBuilder();
private ConnectedThread mConnectedThread;
private ConnectThread mConnectThread;
// SPP UUID service
private static final UUID MY_UUID =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// MAC-address of Bluetooth module (you must edit this line)
private static String address = "00:06:66:60:1D:09";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnOn = (Button) findViewById(R.id.btnOn); //
button LED ON
btnOff = (Button) findViewById(R.id.btnOff); //
button LED OFF
txtArduino = (TextView) findViewById(R.id.txtArduino); // for
display the received data from the Arduino
h = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case receivedMessage:
// if receive massage
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1);
// create string from bytes array
sb.append(strIncom);
// append string
int endOfLineIndex = sb.indexOf("\r\n");
// determine the end-of-line
if (endOfLineIndex > 0) {
// if end-of-line,
String sbprint = sb.substring(0, endOfLineIndex);
// extract string
sb.delete(0, sb.length());
// and clear
txtArduino.setText("Data from Arduino: " +
sbprint); // update TextView
btnOff.setEnabled(true);
btnOn.setEnabled(true);
}
//Log.d(TAG, "...String:"+ sb.toString() + "Byte:" +
msg.arg1 + "...");
break;
}
};
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get
Bluetooth adapter
btnOn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
btnOn.setEnabled(false);
mConnectedThread.write("1"); // Send "1" via Bluetooth
//Toast.makeText(getBaseContext(), "Turn on LED",
Toast.LENGTH_SHORT).show();
}
});
btnOff.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
btnOff.setEnabled(false);
mConnectedThread.write("0"); // Send "0" via Bluetooth
//Toast.makeText(getBaseContext(), "Turn off LED",
Toast.LENGTH_SHORT).show();
}
});
}
@Override
public void onResume() {
super.onResume();
Log.d(TAG, "...onResume - try connect...");
checkBTState();
// Set up a pointer to the remote node using it's address.
BluetoothDevice device = btAdapter.getRemoteDevice(address);
mConnectThread=new ConnectThread(device);
mConnectThread.run();
}
@Override
public void onPause() {
super.onPause();
Log.d(TAG, "...In onPause()...");
//try {
// btSocket.close();
//} catch (IOException e2) {
// errorExit("Fatal Error", "In onPause() and failed to close
socket." + e2.getMessage() + ".");
//}
mConnectedThread.cancel();
}
private void checkBTState() {
// Check for Bluetooth support and then check to make sure it is
turned on
// Emulator doesn't support Bluetooth and will return null
if(btAdapter==null) {
errorExit("Fatal Error", "Bluetooth not support");
} else {
if (btAdapter.isEnabled()) {
Log.d(TAG, "...Bluetooth ON...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new
Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
private void errorExit(String title, String message){
Toast.makeText(getBaseContext(), title + " - " + message,
Toast.LENGTH_LONG).show();
finish();
}
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() {
//android.os.Debug.waitForDebugger();
// Cancel discovery because it will slow down the connection
Log.d(TAG, "prova");
btAdapter.cancelDiscovery();
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
try {
mmSocket.close();
} catch (IOException closeException) { }
return;
}
// Do work to manage the connection (in a separate thread)
mConnectedThread=new ConnectedThread(mmSocket);
mConnectedThread.run();
}
/** 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() {
//android.os.Debug.waitForDebugger();
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.read(buffer);
// Send the obtained bytes to the UI Activity
h.obtainMessage(receivedMessage, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote
device */
public void write(String message) {
Log.d(TAG, "...Data to send: " + message + "...");
byte[] msgBuffer = message.getBytes();
try {
mmOutStream.write(msgBuffer);
} catch (IOException e) {
Log.d(TAG, "...Error data send: " + e.getMessage() + "...");
}
}
/* Call this from the main Activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
}
I also tried an other activity found here which works better but does not
use separated thread to connect. But still has problems as far as it
sometime crashes after resuming, specially if bluetooth is not connected,
or it resumes properly but does not connect to the Arduino BT device.
package com.example.bluetooth2;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.util.UUID;
import com.example.bluetooth2.R;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
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 {
private static final String TAG = "bluetooth2";
Button btnOn, btnOff;
TextView txtArduino;
Handler h;
final int RECIEVE_MESSAGE = 1; // Status for Handler
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder sb = new StringBuilder();
private ConnectedThread mConnectedThread;
// SPP UUID service
private static final UUID MY_UUID =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// MAC-address of Bluetooth module (you must edit this line)
private static String address = "00:06:66:60:1D:09";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnOn = (Button) findViewById(R.id.btnOn); //
button LED ON
btnOff = (Button) findViewById(R.id.btnOff); //
button LED OFF
txtArduino = (TextView) findViewById(R.id.txtArduino); // for
display the received data from the Arduino
h = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case RECIEVE_MESSAGE:
// if receive massage
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1);
// create string from bytes array
sb.append(strIncom);
// append string
int endOfLineIndex = sb.indexOf("\r\n");
// determine the end-of-line
if (endOfLineIndex > 0) {
// if end-of-line,
String sbprint = sb.substring(0, endOfLineIndex);
// extract string
sb.delete(0, sb.length());
// and clear
txtArduino.setText("Data from Arduino: " +
sbprint); // update TextView
btnOff.setEnabled(true);
btnOn.setEnabled(true);
}
//Log.d(TAG, "...String:"+ sb.toString() + "Byte:" +
msg.arg1 + "...");
break;
}
};
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get
Bluetooth adapter
checkBTState();
btnOn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
btnOn.setEnabled(false);
mConnectedThread.write("1"); // Send "1" via Bluetooth
//Toast.makeText(getBaseContext(), "Turn on LED",
Toast.LENGTH_SHORT).show();
}
});
btnOff.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
btnOff.setEnabled(false);
mConnectedThread.write("0"); // Send "0" via Bluetooth
//Toast.makeText(getBaseContext(), "Turn off LED",
Toast.LENGTH_SHORT).show();
}
});
}
private BluetoothSocket createBluetoothSocket(BluetoothDevice device)
throws IOException {
if(Build.VERSION.SDK_INT >= 10){
try {
final Method m =
device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord",
new Class[] { UUID.class });
return (BluetoothSocket) m.invoke(device, MY_UUID);
} catch (Exception e) {
Log.e(TAG, "Could not create Insecure RFComm Connection",e);
}
}
return device.createRfcommSocketToServiceRecord(MY_UUID);
}
@Override
public void onResume() {
super.onResume();
Log.d(TAG, "...onResume - try connect...");
// Set up a pointer to the remote node using it's address.
BluetoothDevice device = btAdapter.getRemoteDevice(address);
// Two things are needed to make a connection:
// A MAC address, which we got above.
// A Service ID or UUID. In this case we are using the
// UUID for SPP.
try {
btSocket = createBluetoothSocket(device);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create
failed: " + e.getMessage() + ".");
}
/*try {
btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create failed: "
+ e.getMessage() + ".");
}*/
// Discovery is resource intensive. Make sure it isn't going on
// when you attempt to connect and pass your message.
btAdapter.cancelDiscovery();
// Establish the connection. This will block until it connects.
Log.d(TAG, "...Connecting...");
try {
btSocket.connect();
Log.d(TAG, "....Connection ok...");
} catch (IOException e) {
try {
btSocket.close();
Log.d(TAG, "Failing connect 1 "+e.getMessage());
} catch (IOException e2) {
Log.d(TAG, "Failing connect 2");
errorExit("Fatal Error", "In onResume() and unable to
close socket during connection failure" + e2.getMessage()
+ ".");
}
}
// Create a data stream so we can talk to server.
Log.d(TAG, "...Create Socket...");
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
}
@Override
public void onPause() {
super.onPause();
Log.d(TAG, "...In onPause()...");
//try {
//btSocket.close();
mConnectedThread.cancel();
//} catch (IOException e2) {
// errorExit("Fatal Error", "In onPause() and failed to close
socket." + e2.getMessage() + ".");
//}
}
private void checkBTState() {
// Check for Bluetooth support and then check to make sure it is
turned on
// Emulator doesn't support Bluetooth and will return null
if(btAdapter==null) {
errorExit("Fatal Error", "Bluetooth not support");
} else {
if (btAdapter.isEnabled()) {
Log.d(TAG, "...Bluetooth ON...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new
Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
private void errorExit(String title, String message){
Toast.makeText(getBaseContext(), title + " - " + message,
Toast.LENGTH_LONG).show();
finish();
}
private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private final BluetoothSocket mmSocket;
public ConnectedThread(BluetoothSocket socket) {
InputStream tmpIn = null;
OutputStream tmpOut = null;
BluetoothSocket tmpSck=null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
tmpSck=socket;
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
mmSocket=tmpSck;
}
public void run() {
android.os.Debug.waitForDebugger();
byte[] buffer = new byte[256]; // 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); // Get number
of bytes and message in "buffer"
h.obtainMessage(RECIEVE_MESSAGE, bytes, -1,
buffer).sendToTarget(); // Send to message queue
Handler
} catch (IOException e) {
break;
} catch (NullPointerException npe) {
Log.d(TAG,npe.getMessage());
}
}
}
/* Call this from the main activity to send data to the remote
device */
public void write(String message) {
Log.d(TAG, "...Data to send: " + message + "...");
byte[] msgBuffer = message.getBytes();
try {
mmOutStream.write(msgBuffer);
} catch (IOException e) {
Log.d(TAG, "...Error data send: " + e.getMessage() + "...");
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
I've read somewhere that Android after ICS has some issue with bluetooth
tied to the OS itself.... I really hope this is not the case... Your help
is greatly appreciated.