public class MyClient extends Thread{

    private DataOutputStream ostream ;
    private DataInputStream istream;
    private Socket socket;

    private boolean isPause;
    private boolean isContinue;

    private String command;

    private final String HOST;
    private final int PORT;
    private final int BUFF_SIZE=64;
    private final GuiElement guiElement;

    public MyClient(String HOST, int PORT,GuiElement guiElement) {
        this.HOST=HOST;
        this.PORT=PORT;
        this.guiElement=guiElement;
        this.isPause=true;
        this.isContinue=true;
        this.setDaemon(true);

        try {
            socket = new Socket(HOST, PORT);
            ostream = new DataOutputStream(socket.getOutputStream());
            istream = new DataInputStream(socket.getInputStream());
        } catch (Exception e) {
            isPause=false;
            isContinue=false;
        }

        start();
    }

    public void run() {

        while(isContinue) {

            //-----waiting
            synchronized(this) {
                while(isPause) {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        closeSocket();
                    }
                }
            }

            //-----sending command
            sendCommand();
        }

        closeSocket();
    }

    //-----invoked from the class that creates this Client thread
    //-----when the user has clicked the enter button on the input field
    synchronized public void setCommand(String command) {
        this.command=command;
        isPause=false;
        notify();
    }

    private void sendCommand() {

        try {
            ostream.write(command.getBytes());
            ostream.flush();

            byte buf[] = new byte[BUFF_SIZE];
            int r;

            r = istream.read(buf);
            String data = new String(buf, 0, r);

        } catch (Exception e) {
            closeSocket();
        }
        Platform.runLater(() -> guiElement.print(data)); /* display a message on a GUI element  */
        isPause=true;
    }

    private void closeSocket() {
        try {
            if(socket.isClosed())return;
            else socket.close();
        } catch (Exception e) {
            isPause=false;
            isContinue=false;
        }
    }
}