Open a comm port and send an ASCII string

Question

This is my first ever project and first GUI. I have finished it (with help from Stack Overflow) and it works but is very slow. Can anyone suggest improvements for speed, best practices or usability.?

It currently takes 16 seconds from pressing run in Eclipse to something appearing on my screen. You will need RXTX lib to run it.

This is my GUI:

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.NoSuchPortException;
import gnu.io.SerialPort;

import java.util.HashMap;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseAdapter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import javax.swing.JTextArea;
import javax.swing.JLabel;
import javax.swing.JComboBox;
import javax.swing.SwingUtilities;
import java.awt.Window.Type;
import java.awt.Frame;
import java.awt.Rectangle;
import java.io.IOException;
import javax.swing.JTextField;
import javax.swing.JScrollPane;




public class EBIAlarmUI extends JFrame {

private static final long serialVersionUID = 16022014;

public TwoWaySerialComm twoWaySerCom;


/**
 * Start the GUI
 */

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {


            try {
                EBIAlarmUI frame = new EBIAlarmUI();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

}

/**
 * Create the frame.
 */
public EBIAlarmUI() {
    initComponents();
    twoWaySerCom = new TwoWaySerialComm();
    redirectSystemStreams();

}


private void initComponents(){


    setBounds(new Rectangle(0, 0, 1000, 600));
    setExtendedState(Frame.MAXIMIZED_HORIZ);
    setType(Type.POPUP);
    setAlwaysOnTop(true);
    setTitle("Alarm Generator");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    GridBagLayout gridBagLayout = new GridBagLayout();
    gridBagLayout.columnWidths = new int[]{0, 118, 0, 0, 0, 0, 0, 17, 23, 0, 0};
    gridBagLayout.rowHeights = new int[]{0, 0, 0, 0, 0, 0, 0, 0, 0};
    gridBagLayout.columnWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, Double.MIN_VALUE};
    gridBagLayout.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, Double.MIN_VALUE};
    getContentPane().setLayout(gridBagLayout);

    JLabel setComPortLabel = new JLabel("Com Port");
    GridBagConstraints gbc_setComPortLabel = new GridBagConstraints();
    gbc_setComPortLabel.anchor = GridBagConstraints.EAST;
    gbc_setComPortLabel.insets = new Insets(0, 0, 5, 5);
    gbc_setComPortLabel.gridx = 0;
    gbc_setComPortLabel.gridy = 2;
    getContentPane().add(setComPortLabel, gbc_setComPortLabel);

    comPortcomboBox = new JComboBox();
    comPortcomboBox.setEnabled(true);
    setComPortLabel.setLabelFor(comPortcomboBox);
    GridBagConstraints gbc_comPortcomboBox = new GridBagConstraints();
    gbc_comPortcomboBox.fill = GridBagConstraints.HORIZONTAL;
    gbc_comPortcomboBox.insets = new Insets(0, 0, 5, 5);
    gbc_comPortcomboBox.gridx = 1;
    gbc_comPortcomboBox.gridy = 2;
    getContentPane().add(comPortcomboBox, gbc_comPortcomboBox);
    Enumeration portList = CommPortIdentifier.getPortIdentifiers();

    while (portList.hasMoreElements()) {
      CommPortIdentifier cpi = (CommPortIdentifier) portList.nextElement();

      if (cpi.getPortType() == CommPortIdentifier.PORT_SERIAL) {
              comPortcomboBox.addItem(cpi.getName());

        }

      }

     comPortcomboBox.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                comPortcomboBoxActionPerformed(evt);
            }

    public void comPortcomboBoxActionPerformed(java.awt.event.ActionEvent evt) {
        comPortcomboBox.getSelectedItem();



     }

});

    alarm1Button = new JButton();
    alarm1Button.setText("Alarm 1");
    GridBagConstraints gbc_alarm1Button = new GridBagConstraints();
    gbc_alarm1Button.insets = new Insets(0, 0, 5, 0);
    gbc_alarm1Button.gridx = 9;
    gbc_alarm1Button.gridy = 2;
    getContentPane().add(alarm1Button, gbc_alarm1Button);

    alarm1Button.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            alarm1ButtonActionPerformed(evt);
        }
        public synchronized void alarm1ButtonActionPerformed(
                java.awt.event.ActionEvent evt) {
            resultsTextArea.setText("Alarm 1 Activated, String: " + alarm1);

            try {

                byte[] b = alarm1.getBytes("ASCII");

                TwoWaySerialComm.SerialWriter sw = new TwoWaySerialComm.SerialWriter(
                        twoWaySerCom.serialPort.getOutputStream());

                sw.out.write(b);
            } catch (IOException e) {
                // Do something to handle the exception
                e.printStackTrace();
            }
        }
    });

    JButton alarm2Button = new JButton("Alarm 2");
    alarm2Button.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            alarm2ButtonActionPerformed(evt);
        }
        public synchronized void alarm2ButtonActionPerformed(
                java.awt.event.ActionEvent evt) {
            resultsTextArea.setText("Alarm 2 Activated, String: " + alarm2);

            try {

                byte[] b = alarm2.getBytes("ASCII");

                TwoWaySerialComm.SerialWriter sw = new TwoWaySerialComm.SerialWriter(
                        twoWaySerCom.serialPort.getOutputStream());

                sw.out.write(b);
            } catch (IOException e) {
                // Do something to handle the exception
                e.printStackTrace();
            }
        }
    });

    JLabel setBaudRateLabel = new JLabel("Baud Rate");
    GridBagConstraints gbc_setBaudRateLabel = new GridBagConstraints();
    gbc_setBaudRateLabel.anchor = GridBagConstraints.EAST;
    gbc_setBaudRateLabel.insets = new Insets(0, 0, 5, 5);
    gbc_setBaudRateLabel.gridx = 0;
    gbc_setBaudRateLabel.gridy = 3;
    getContentPane().add(setBaudRateLabel, gbc_setBaudRateLabel);

    baudRatecomboBox = new JComboBox(baudRates);
    baudRatecomboBox.setSelectedIndex(2);
    setBaudRateLabel.setLabelFor(baudRatecomboBox);
    GridBagConstraints gbc_baudRateComboBox = new GridBagConstraints();
    gbc_baudRateComboBox.fill = GridBagConstraints.HORIZONTAL;
    gbc_baudRateComboBox.insets = new Insets(0, 0, 5, 5);
    gbc_baudRateComboBox.gridx = 1;
    gbc_baudRateComboBox.gridy = 3;
    getContentPane().add(baudRatecomboBox, gbc_baudRateComboBox);
    GridBagConstraints gbc_alarm2Button = new GridBagConstraints();
    gbc_alarm2Button.insets = new Insets(0, 0, 5, 0);
    gbc_alarm2Button.gridx = 9;
    gbc_alarm2Button.gridy = 3;
    getContentPane().add(alarm2Button, gbc_alarm2Button);

    JButton alarm3Button = new JButton("Alarm 3");
    alarm3Button.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            alarm3ButtonActionPerformed(evt);
        }
        public synchronized void alarm3ButtonActionPerformed(
                java.awt.event.ActionEvent evt) {
            resultsTextArea.setText("Alarm 3 Activated, String: " + alarm3);

            try {

                byte[] b = alarm3.getBytes("ASCII");

                TwoWaySerialComm.SerialWriter sw = new TwoWaySerialComm.SerialWriter(
                        twoWaySerCom.serialPort.getOutputStream());

                sw.out.write(b);
            } catch (IOException e) {
                // Do something to handle the exception
                e.printStackTrace();
            }
        }
    });

    JLabel lblDataBits = new JLabel("Data Bits");
    GridBagConstraints gbc_lblDataBits = new GridBagConstraints();
    gbc_lblDataBits.insets = new Insets(0, 0, 5, 5);
    gbc_lblDataBits.anchor = GridBagConstraints.EAST;
    gbc_lblDataBits.gridx = 0;
    gbc_lblDataBits.gridy = 4;
    getContentPane().add(lblDataBits, gbc_lblDataBits);

    dataBitscomboBox = new JComboBox(dataBits);
    dataBitscomboBox.setSelectedIndex(1);
    GridBagConstraints gbc_dataBitscomboBox = new GridBagConstraints();
    gbc_dataBitscomboBox.insets = new Insets(0, 0, 5, 5);
    gbc_dataBitscomboBox.fill = GridBagConstraints.HORIZONTAL;
    gbc_dataBitscomboBox.gridx = 1;
    gbc_dataBitscomboBox.gridy = 4;
    getContentPane().add(dataBitscomboBox, gbc_dataBitscomboBox);

    GridBagConstraints gbc_alarm3Button = new GridBagConstraints();
    gbc_alarm3Button.insets = new Insets(0, 0, 5, 0);
    gbc_alarm3Button.gridx = 9;
    gbc_alarm3Button.gridy = 4;
    getContentPane().add(alarm3Button, gbc_alarm3Button);

    JLabel lblStopBits = new JLabel("Stop Bits");
    GridBagConstraints gbc_lblStopBits = new GridBagConstraints();
    gbc_lblStopBits.insets = new Insets(0, 0, 5, 5);
    gbc_lblStopBits.anchor = GridBagConstraints.EAST;
    gbc_lblStopBits.gridx = 0;
    gbc_lblStopBits.gridy = 5;
    getContentPane().add(lblStopBits, gbc_lblStopBits);

    stopBitscomboBox = new JComboBox(stopBits);
    stopBitscomboBox.setSelectedIndex(1);
    GridBagConstraints gbc_stopBitscomboBox = new GridBagConstraints();
    gbc_stopBitscomboBox.insets = new Insets(0, 0, 5, 5);
    gbc_stopBitscomboBox.fill = GridBagConstraints.HORIZONTAL;
    gbc_stopBitscomboBox.gridx = 1;
    gbc_stopBitscomboBox.gridy = 5;
    getContentPane().add(stopBitscomboBox, gbc_stopBitscomboBox);

    JButton customAlarmButton = new JButton("Custom Alarm");
    GridBagConstraints gbc_customAlarmButton = new GridBagConstraints();
    gbc_customAlarmButton.insets = new Insets(0, 0, 5, 0);
    gbc_customAlarmButton.gridx = 9;
    gbc_customAlarmButton.gridy = 5;
    getContentPane().add(customAlarmButton, gbc_customAlarmButton);

    customAlarmButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            customAlarmButtonActionPerformed(evt);
        }
        public void customAlarmButtonActionPerformed(java.awt.event.ActionEvent evt) {
                resultsTextArea.setText("Custom alarm, string sent: "+ customStringTextArea.getText());

                try {
                    byte[] b = customStringTextArea.getText().toString().getBytes("ASCII");

                    TwoWaySerialComm.SerialWriter sw = new TwoWaySerialComm.SerialWriter(
                            twoWaySerCom.serialPort.getOutputStream());

                    sw.out.write(b);
                } catch (IOException e) {
                    // Do something to handle the exception
                    e.printStackTrace();
                }
            }
        });

    JLabel lblParity = new JLabel("Parity");
    GridBagConstraints gbc_lblParity = new GridBagConstraints();
    gbc_lblParity.insets = new Insets(0, 0, 5, 5);
    gbc_lblParity.anchor = GridBagConstraints.EAST;
    gbc_lblParity.gridx = 0;
    gbc_lblParity.gridy = 6;
    getContentPane().add(lblParity, gbc_lblParity);

    paritycomboBox = new JComboBox(parity);
    paritycomboBox.setSelectedIndex(0);
    GridBagConstraints gbc_paritycomboBox = new GridBagConstraints();
    gbc_paritycomboBox.insets = new Insets(0, 0, 5, 5);
    gbc_paritycomboBox.fill = GridBagConstraints.HORIZONTAL;
    gbc_paritycomboBox.gridx = 1;
    gbc_paritycomboBox.gridy = 6;
    getContentPane().add(paritycomboBox, gbc_paritycomboBox);

    JLabel customStringAreaLabel = new JLabel("Enter Custom String:");
    GridBagConstraints gbc_customStringAreaLabel = new GridBagConstraints();
    gbc_customStringAreaLabel.insets = new Insets(0, 0, 5, 5);
    gbc_customStringAreaLabel.gridx = 6;
    gbc_customStringAreaLabel.gridy = 6;
    getContentPane().add(customStringAreaLabel, gbc_customStringAreaLabel);

    customStringTextArea = new JTextArea();
    GridBagConstraints gbc_customStringTextArea = new GridBagConstraints();
    gbc_customStringTextArea.gridwidth = 3;
    gbc_customStringTextArea.insets = new Insets(0, 0, 5, 0);
    gbc_customStringTextArea.fill = GridBagConstraints.BOTH;
    gbc_customStringTextArea.gridx = 7;
    gbc_customStringTextArea.gridy = 6;
    getContentPane().add(customStringTextArea, gbc_customStringTextArea);
    customStringTextArea.setText("Enter Custom String Here");
    customStringTextArea.addMouseListener(new java.awt.event.MouseAdapter() {

        public void mousePressed(java.awt.event.MouseEvent evt) {
            customStringTextAreaMousePressed(evt);
        }

         private void customStringTextAreaMousePressed(java.awt.event.MouseEvent evt) {
             customStringTextArea.setText("");
        }

        });

    openComportButton = new JButton("Open");
    GridBagConstraints gbc_openComportButton = new GridBagConstraints();
    gbc_openComportButton.anchor = GridBagConstraints.NORTH;
    gbc_openComportButton.insets = new Insets(0, 0, 0, 5);
    gbc_openComportButton.gridx = 0;
    gbc_openComportButton.gridy = 7;
    getContentPane().add(openComportButton, gbc_openComportButton);

    openComportButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            openComportButtonActionPerformed(evt);
        }
        public synchronized void openComportButtonActionPerformed(
                java.awt.event.ActionEvent evt)  {
            resultsTextArea.setText("Com Port Opened");
            String port = (String)comPortcomboBox.getSelectedItem();
            String rate = (String)baudRatecomboBox.getSelectedItem();
            String data = (String)dataBitscomboBox.getSelectedItem();
            String stop = (String)stopBitscomboBox.getSelectedItem();
            int parity = (int)paritycomboBox.getSelectedIndex();
            int rateInt = Integer.parseInt(rate);
            int dataInt = Integer.parseInt(data);
            int stopInt = Integer.parseInt(stop);

            if (port != null && rate != null && data != null && stop != null) {


                        try {
                            twoWaySerCom.connect(port, rateInt, dataInt, stopInt, parity);
                        } catch (Exception e) {

                            e.printStackTrace();
                        }
                    } 
        }
    });


    closeComportButton = new JButton("Close");
    GridBagConstraints gbc_closeComportButton = new GridBagConstraints();
    gbc_closeComportButton.anchor = GridBagConstraints.NORTHWEST;
    gbc_closeComportButton.insets = new Insets(0, 0, 0, 5);
    gbc_closeComportButton.gridx = 1;
    gbc_closeComportButton.gridy = 7;
    getContentPane().add(closeComportButton, gbc_closeComportButton);

    closeComportButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            closeComportButtonActionPerformed(evt);
        }
        public synchronized void closeComportButtonActionPerformed(
                java.awt.event.ActionEvent evt)  {

            resultsTextArea.setText("Com Port Closed");
            try {
                twoWaySerCom.disconnect();
            } catch (Exception e) {

                e.printStackTrace();
            }
        } 


        });

    JLabel resultAreaLabel = new JLabel("Result:");
    GridBagConstraints gbc_resultAreaLabel = new GridBagConstraints();
    gbc_resultAreaLabel.anchor = GridBagConstraints.NORTHEAST;
    gbc_resultAreaLabel.insets = new Insets(0, 0, 0, 5);
    gbc_resultAreaLabel.gridx = 6;
    gbc_resultAreaLabel.gridy = 7;
    getContentPane().add(resultAreaLabel, gbc_resultAreaLabel);

    JScrollPane scrollPane = new JScrollPane();
    GridBagConstraints gbc_scrollPane = new GridBagConstraints();
    gbc_scrollPane.gridwidth = 8;
    gbc_scrollPane.fill = GridBagConstraints.BOTH;
    gbc_scrollPane.gridx = 7;
    gbc_scrollPane.gridy = 7;

    getContentPane().add(scrollPane, gbc_scrollPane);


    resultsTextArea = new JTextArea();
    scrollPane.setViewportView(resultsTextArea);
    resultsTextArea.setLineWrap(true);




}
public void updateTextArea(final String text) {
      SwingUtilities.invokeLater(new Runnable() {
        public void run() {
          resultsTextArea.append(text);
        }
      });
    }

    public void redirectSystemStreams() {
      OutputStream out = new OutputStream() {
        @Override
        public void write(int b) throws IOException {
          updateTextArea(String.valueOf((char) b));
        }

        @Override
        public void write(byte[] b, int off, int len) throws IOException {
          updateTextArea(new String(b, off, len));
        }

        @Override
        public void write(byte[] b) throws IOException {
          write(b, 0, b.length);
        }
      };

      System.setOut(new PrintStream(out, true));
      System.setErr(new PrintStream(out, true));
    }
public javax.swing.JTextArea resultsTextArea;
public javax.swing.JTextArea customStringTextArea;
public javax.swing.JButton alarm1Button;
public javax.swing.JButton alarm2Button;
public javax.swing.JButton alarm3Button;
public javax.swing.JButton customAlarmButton;
public javax.swing.JButton openComportButton;
public javax.swing.JButton closeComportButton;

protected HashMap map = new HashMap();
public javax.swing.JComboBox comPortcomboBox;
public javax.swing.JComboBox baudRatecomboBox;
public javax.swing.JComboBox dataBitscomboBox;
public javax.swing.JComboBox stopBitscomboBox;
public javax.swing.JComboBox paritycomboBox;



String alarm1 = "81 01 06 01 00 10 03 01 FF";
String alarm2 = "*993R03,67,6#";
String alarm3 = "*994R14,67,1#";
String[] parity = { "none", "odd", "even", "mark" };
String[] baudRates = { "2400", "4800", "9600", "14400", "19200", "38400", "56000", "115200"  };
String[] stopBits = { "0", "1"  };
String[] dataBits = { "7", "8"  };


}

And this is where my comm port is opened and closed:

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class TwoWaySerialComm {

SerialPort serialPort;

public TwoWaySerialComm() {
    super();
}

public synchronized void connect(String port, int rateInt, int dataInt, int stopInt, int parity) throws Exception {

    CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(port);
    if (portIdentifier.isCurrentlyOwned()) {

        System.out.println("Error: Port is currently in use");
    } else {
        CommPort commPort = portIdentifier.open(this.getClass().getName(),
                2000);

        if (commPort instanceof SerialPort) {
            serialPort = (SerialPort) commPort;
            serialPort.setSerialPortParams(rateInt, dataInt, stopInt, parity);

            InputStream in = serialPort.getInputStream();
            OutputStream out = serialPort.getOutputStream();

            (new Thread(new SerialReader(in))).start();
            (new Thread(new SerialWriter(out))).start();

        } else {
            System.out
                    .println("Error: Only serial ports are handled by this.");
        }
    }
}
public synchronized void disconnect() throws Exception {
    if (serialPort != null) {
        InputStream in = serialPort.getInputStream();
        OutputStream out = serialPort.getOutputStream();
        try {

            serialPort.removeEventListener();

            in.close();
            out.close();
        } catch (IOException ex) {

        }

        serialPort.close();
    }

}
/** */
public class SerialReader implements Runnable {
    InputStream in;

    public SerialReader(InputStream in) {
        this.in = in;
    }

    public void run() {
        byte[] buffer = new byte[1024];
        int len = -1;
        try {
            while ((len = this.in.read(buffer)) > -1) {
                System.out.print(new String(buffer, 0, len));

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

/** */
public static class SerialWriter implements Runnable {
    OutputStream out;

    public SerialWriter(OutputStream out) {
        this.out = out;
    }

    public void run() {
        try {
            int c = 0;
            while ((c = System.in.read()) > -1) {
                this.out.write(c);
                System.out.println(c);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

}

Answer 1

Finding Performance Problems

It currently takes 16 seconds from pressing run in Eclipse to something appearing on my screen.

The first step to fixing this is to find out what is causing the delay. My first assumption would be that it is the hardware on the other end of the connection, but who knows. To figure this out, you can do two things:

• Mock the TwoWaySerialComm object, so that there is no real communication with any external device. If your performance problems go away, you know it's not the GUI, but the external device, or the way you communicate with it*.
• Profile your code and see which methods take the longest.

Before you don't know what the problem is, it will be hard to suggest improvements.

_{* the communication itself seems to be happening in a different thread, but not the initial connection. As you say you have performance problems on startup, this might be an issue.}

Structure

It's really good that you put the connection stuff in it's own TwoWaySerialComm class. But right now, this class is hard to use, as you are printing in it, and swallowing exceptions. As you have a GUI, it would be nice to report errors in the GUI, not on the command line. So your TwoWaySerialComm class should throw exceptions instead of printing the errors.

Your fields should also be private and accessed with getters.

The biggest problem with your code structure is your GUI class though: It's way too big, and it has a method with 360 lines, which is just way too much. Nobody is going to read or understand that later on, and it makes your code very hard to extend, debug, profile, reuse, etc.

This gigantic method also contains a lot of duplication, for example the alarmXButtonActionPerformed ActionListener are pretty much the same. Create an actual class for them, and pass the button as argument. This would already help quite a bit.

If you then extract some of the GUI init code that logically belongs to each other to well-named functions, this would already be a great first step.

Misc

• your naming could be better in parts. Eg it took me a bit to figure out what gbc_lblParity are. Don't shorten names, and use java naming conventions (camelCase). parityLabel and parityGridBagConstraints (or parityConstraints) aren't all that long, but a lot clearer

Answer 2

UPDATE

After further review of your code, delay is likely in the getPortIdentifiers(). That is where I'd look first. For purposes of locating the delay, bypass getPortIdentifiers().

You could hard code the device name and to run the code without getting the list.

And / or when making your list of ports, save the time it takes for each iteration of the while (portList.hasMoreElements()) loop. Associate the times with the port name. You may have a port(s) with a long timeout introducing the delay. You may want to add port status to the list of PORT_SERIAL ports including open/available, DSR and CTS.

About the Flow control in my previous post.

I did not see anywhere in your code you turn off hardware hand shaking FLOWCONTROL_NONE. What is your flow control? getFlowControlMode()

Even when Hardware Handshaking is not used by the device most PC's still support it. The reason I suggested what I did is because I was thinking the delay was likely a hardware/firmware port setup issue or a client initialization issue.

The serial port must still have the hardware handshaking disabled (not recommended for diagnostic purposes) or have the signals driven active in order for the UART to work.

---

Original Post

if (commPort instanceof SerialPort) {
            serialPort = (SerialPort) commPort;
            serialPort.setSerialPortParams(rateInt, dataInt, stopInt, parity);

At this point in your code

Assert RTS and DTR

Then Check Port Status by reading DSR and CTS

If the device you are connected to does not support hardware handshaking they may have these signal set to an active state or they may be left unconnected. If these signal are not driven by the connected device, be sure your cable loops back your DSR and CTS to your DTR and RTS. Or use an RS-232 loop back adapter.

Keeping in mind the PC is a DTE (Data Terminal Equipment) device not DCE (Data data Communication Equipment)

When designing the original PC IBM perceived the PC to be a Terminal to their Big Iron so the logic of DTE and DCE are reversed.

DTR Out (Data Terminal Ready)
DSR In  (Data Set Ready) 
RTS Out (Request to Send) 
CTS In  (Clear to Send)

When dealing with Serial devices you have to keep in mind diagnostics. When things are not working, where is the problem?

Avoid devices that do not drive the DTR and RTS signal.
The troubleshooting procedure is to read DTR and RTS then disconnect connect the cable and read them again and see if their was a change in port status.

If the serial port is a USB to RS-232 adapter, the device driver may always report DSR and CTS as active regardless if the connected device's actual DSR and CTS signals.

Many times the Available and the Port number the device is connect to is unknown. You should include a routine that reads the status of all ports supported by the OS and report the status of each port. If a port exists at that port number read DSR and CTS and include in the report.

Most serial device support the Hayes AT Command. If so, issue a command and read the response as part of the device initialization routine.