Re: Reading mouse input with Java comm

Knute Johnson <>
Sat, 05 Apr 2008 15:30:48 -0700
Steve wrote:

Hi Folks...

I'm trying to get a Java program together to read the input from a
serial mouse connected to my PC on COM1. This is not the main mouse so
I don't get a port in use exception when I start the program. The
problem is that I get absolutely nothing.

I've constructed this from scraps I've found all over the internet.
I'm using version 2.1.7 of the RXTX comm API hence the ''
package prefixes.

I'd be most grateful if anyone has a suggestion on why this doesn't
work. Or indeed any step I might take to ensure the mouse if connected
properly to the PC.

With thanks in advance,



public final class CommServiceManager {
    public void initialise() throws Exception {
        CommPortIdentifier portId =
        SerialPort serialPort = (SerialPort)"MouseReader",
        final InputStream inputStream = serialPort.getInputStream();
        serialPort.addEventListener(new SerialPortEventListener() {
            public void serialEvent(SerialPortEvent evt) {
                if (evt.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
                    byte[] readBuffer = new byte[20];
                    try {
                        while (inputStream.available() > 0)

                        System.out.println(">>" + new String(readBuffer));
                    } catch (IOException ioe) {





        int duration = 1000;
        float pulseRate = 1.28f;
        int numOfPulse = (int) (duration * pulseRate);

        int waitingTime = (int) (1000 / (2 * pulseRate));
        for (int i = 1; i <= numOfPulse * 2; i++) {
            serialPort.setDTR(i % 2 == 1);

    public static void main(String[] args) {
        try {
            CommServiceManager manager = new CommServiceManager();

            while (true) {
        } catch (Exception e) {

Is this being used on a Windows machine? If it is you need to use Sun's
JavaComm implementation. RXTX on Windows is seriously broken.

As to your code, I don't think you are looking long enough to find anything.

Does a serial mouse return characters? I've never tried it.

Let me know if you are using Windows, if so I'll scrounge around in my
garage to find one that I think is down there and give it a try.


Knute Johnson
email s/nospam/linux/

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