// class variables used for communication:
private String readline = "";
private String comPort = "COM5"; // change this port to the current one from the Arduino IDE
private SerialPort port;

/**
  * Connect to COM-port specified in class-variable comPort.
  * Setup an eventlistener to respond to data send from Arduino.
  * Based on:
  * jSerialComm Event-Based Reading Usage Example
  * https://github.com/Fazecast/jSerialComm/wiki/Event-Based-Reading-Usage-Example
  */
public void connect() {
    /*
    // get a list of available ports:
    SerialPort ports[] = SerialPort.getCommPorts();
    for (int i = 0; i < ports.length; ++i) {
        System.out.println(ports[i].getDescriptivePortName());
    }
    // comPort = SerialPort.getCommPorts()[0];
    */
    System.out.println("Connecting to "+comPort+" ...");
    port = SerialPort.getCommPort(comPort);
    port.openPort();
    port.addDataListener(new SerialPortDataListener() {
        @Override
        public int getListeningEvents() {
            return SerialPort.LISTENING_EVENT_DATA_AVAILABLE;
        }

        @Override
        public void serialEvent(SerialPortEvent event) {
            if (event.getEventType() != SerialPort.LISTENING_EVENT_DATA_AVAILABLE)
                return;
            byte[] newData = new byte[port.bytesAvailable()];
            int numRead = port.readBytes(newData, newData.length);
            // System.out.println("Read " + numRead + " bytes.");
            if (numRead > 0) {
                for (int i = 0; i < newData.length; ++i) {
                    if ((char)newData[i]=='\n'||(char)newData[i]=='\r') {
                        readline=readline.trim();
                        if (readline.length()>0) receive(readline);
                        readline="";
                    }
                    else
                        readline=readline+(char)newData[i];
                }
            }
        }
    });
} // end of method connect()

/**
  * If a line of text is received, process it
  * @param line
  */
private void receive(String line) {
    System.out.println(line);
} // end of method receive()

/**
  * Send a message m to the connected COM-port
  * @param m
  */
public void send(String m) {
    port.writeBytes(m.getBytes(), m.length());
} // end of method send()