Server cannot show string

[nida azizah]

hi.

i recreate a server program in my pc that can read any input (string) from client(android) which is transmitted via bluetooth (kinda like bluetooth chat). The problem is my server seems cannot show string immediately after i send it from my client, it'll only appeared after i turn off the bluetooth and the connection was cut, also it won't send response string to client. already try to put pWriter.flush() to make string shows, but it doesn't works. can you tell me what's wrong with my program? thank you.

here is my program :

public class ServerBluetooth2 {
    //start server
    private void startServer() throws IOException{

        //Create a UUID for SPP
        UUID uuid = new UUID("1101", true);
        //Create the servicve url
        String connectionString = "btspp://localhost:" + uuid +";name=Server Bluetooth 2";

        //open server url
        StreamConnectionNotifier streamConnNotifier = (StreamConnectionNotifier)Connector.open( connectionString );

        //Wait for client connection
        System.out.println("\nServer Started. Waiting for clients to connect...");
        StreamConnection connection=streamConnNotifier.acceptAndOpen();

        RemoteDevice dev = RemoteDevice.getRemoteDevice(connection);
        System.out.println("Remote device address: "+dev.getBluetoothAddress());
        System.out.println("Remote device name: "+dev.getFriendlyName(true));

    
    InputStream inStream=connection.openInputStream();
    BufferedReader bReader=new BufferedReader(new InputStreamReader(inStream));
    String lineRead=bReader.readLine();
    System.out.println(lineRead);


    OutputStream outStream=connection.openOutputStream();
    PrintWriter pWriter=new PrintWriter(new OutputStreamWriter(outStream));
    pWriter.write("Response String from SPP Server\r\n");
    pWriter.flush();
    streamConnNotifier.close();
    
    }

    public static void main(String[] args) throws IOException {

        //display local device address and name
        LocalDevice localDevice = LocalDevice.getLocalDevice();
        System.out.println("Address: "+localDevice.getBluetoothAddress());
        System.out.println("Name: "+localDevice.getFriendlyName());

        ServerBluetooth2 serverbluetooth2=new ServerBluetooth2();
        serverbluetooth2.startServer();

    }
}

[Tony Docherty]

Can you show the client code as well please and does it use flush() as well.

[nida azizah]

i though it'll be different when i'm programming using android studio so i'm not using flush();. do i have to use it too? sorry, i am new to java.

here's my code in client to read and write my string:

    // runs during a connection with a remote device
    private class ConnectedThread extends Thread {
        private final BluetoothSocket bluetoothSocket;
        private final InputStream inputStream;
        private final OutputStream outputStream;

        public ConnectedThread(BluetoothSocket socket, String socketType) {
            this.bluetoothSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;

            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) {
            }

            inputStream = tmpIn;
            outputStream = tmpOut;
        }

        public void run() {
            byte[] buffer = new byte[1024];
            int bytes;

            // Keep listening to the InputStream
            while (true) {
                try {
                    // Read from the InputStream
                    bytes = inputStream.read(buffer);

                    // Send the obtained bytes to the UI Activity
                    handler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1,
                            buffer).sendToTarget();
                } catch (IOException e) {
                    connectionLost();
                    // Start the service over to restart listening mode
                    ChatService.this.start();
                    break;
                }
            }
        }

        // write to OutputStream
        public void write(byte[] buffer) {
            try {
                outputStream.write(buffer);
                handler.obtainMessage(MainActivity.MESSAGE_WRITE, -1, -1,
                        buffer).sendToTarget();
            } catch (IOException e) {
            }
        }

        public void cancel() {
            try {
                bluetoothSocket.close();
            } catch (IOException e) {
            }
        }
    }

Thanks for your help.

[Tony Docherty]

Sorry I've never programmed for android so I can't give you a definitive answer to that but I would have thought you would have needed to call flush().

[nida azizah]

I thought the problem is occurred on my server sides because i already change my client program several times but the result on server is still same. do you have any idea or some suggestions regarding my server sides?

[Tony Docherty]

The problem with not calling flush() in the client code (assuming the android stuff works the same as standard Java) is the client is unlikely to send the string until the connection is being closed (or the buffer fills up) so the server will just sit there waiting for the message from the client.

[Ron McLeod]

To help determine if it is a client-side problem or a server-side problem, try using a running an Android Bluetooth terminal emulator client, and see if the behaviour on the server changes.