How to Use Classes - Bluetooth Thread

Question

I'm trying to connect android and arduino and send data between them. I am following the guide http://developer.android.com/guide/topics/connectivity/bluetooth.html#ManagingAConnection

I think I vaguely understand how this works but I don't have a complete mastery of the basics so I am a bit stuck.

I am looking at the code for "connecting as a client":

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
    mBluetoothAdapter.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)
    manageConnectedSocket(mmSocket);
}

/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
    try {
        mmSocket.close();
    } catch (IOException e) { }
}
}

and for "managing connection"

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.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) { }
}
}

I basically copied the exact code and made new java files containing them. I want to actually use these classes to send data so I paired the devices and then found the IDs like:

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
    if (pairedDevices.size() > 0) 
    {
        // Loop through paired devices
        for (BluetoothDevice device : pairedDevices) 
        {
            if (device.getName().equals("HC-06"))
            {
                //NEED TO INSERT CODE HERE (I think...)             
            }
            else
            {
                Intent intentneedsetting = new Intent(this, NeedSettingsActivity.class);       
                startActivity(intentneedsetting);
            }
        }
    }
    else
    {
        Intent intentneedsetting = new Intent(this, NeedSettingsActivity.class);       
        startActivity(intentneedsetting);
    } 

Any help regarding how to use these classes (ConnectThread/ConnectedThread) will be very appreciated!

Answer 1

I'm not sure what did you vaguley understood and what not but i'll try to explain the purpose of these classes in general..

ConnectThread - receives a bluetooth device that was discovered in the discovery stage (which is prior to connection obviously) gets the BT socket from the device and when run() is called it tries to connect to it. if the connection succeeded - in the code it just says manageConnectedSocket(mmSocket); but that means that u should open a ConnectedThread for receiving and sending data through the socket.

ConnectedThread - as mentioned, is the thread for managing sending and receiving data. as you can see in the run() it constantly listens using a while(true) it calls read which is blocking - meaning "the thread is stuck there" until it receives incoming data. When data is received it handles it with the mHandler which is also not implemented here, again you should just implement whatever you want to do with the data received. The write method simply receives an array of bytes and writes it to the socket, note that this is also a blocking call therefore u should use it from another thread.

Hope this helps u understand