Java SocketException: Connection reset,. What is the cause?

Question

I wrote a simple client-server program. The client connects to the server, then sends a message to the server. The server prints the message. My problem is that I don't understand why I get a SocketException: Connection reset exception when I don't call the sendMessageToServer() method. When I call the method everything works without an exception.

public class Client
{
    private Socket socket;

    public  Client(int port) throws IOException
    {
        this.socket = new Socket(InetAddress.getLocalHost(), port);
       // sendMessageToServer("Hello Server!\n");
    }

    public void sendMessageToServer(String message) throws IOException
    {
        try (BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));)
        {
            bufferedWriter.write(message);

        }
        catch (IOException ioe)
        {
            ioe.printStackTrace();
        }

    }

}

public class Server
{
    private ServerSocket serverSocket;

    ExecutorService executorService = Executors.newFixedThreadPool(3);

    public Server(int port, int backlog, InetAddress inetAddress) throws IOException
    {
            this.serverSocket = new ServerSocket(port, backlog, inetAddress);
    }

    public void startListening() throws IOException
    {
        System.out.println("Listening...");

        while (true)
        {
           ClientHandler clientHandler = new ClientHandler(serverSocket.accept());
           System.out.println("Connected");
           executorService.execute(clientHandler);
           System.out.println("Waiting for another client");
        }
    }

}

public class ClientHandler implements Runnable
{
   private Socket clientSocket;

   public ClientHandler(Socket socket)
   {
       clientSocket = socket;
   }

    @Override
    public void run()
    {

        try (
                // read from client
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        )
        {

            // read message from client
            String message = "";
            String line = "";
            while ((line = bufferedReader.readLine()) != null)
            {
                message += line;
            }

            System.out.println("Client message = " + message);


        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

    }
}

I expected that if I did not call the sendMessageToServer() method then the server would write out an empty message.