Getting started in Java Comm API

Question

Hi This is all new to me. So I would really appreciate if anyone can help me figure this out..I am trying to read from the serial port using a VS4000 Image Scanner(Symbol). I want to scan a driver's license bar code. I believe PDF417 is the type of barcode to read driver's license. However, Im just curious if there is any code out there that actually parses the information out of the license. I need to get the lastname, firstname,dob,gender,address,drivers #, etc.. Does any one have any idea where I could get more information in how to scan a driver's license. I need more guidance in how to really do this. Although, I went to the introduction to Java Communications and found a example code "SimpleRead.java". However, I get some errors....
can anyone help..I have a nullpointer ..not sure how to fix it...
I get this error :
java.lang.NullPointerException
     at SimpleRead.<init>(SimpleRead.java:64)
     at SimpleRead.main(SimpleRead.java:53)
Exception in thread "main" Process terminated with exit code 1
Here is the original code :
import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleRead implements Runnable, SerialPortEventListener {
static CommPortIdentifier portId;
static Enumeration portList;
InputStream inputStream;
SerialPort serialPort;
Thread readThread;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
if (portId.getName().equals("COM1")) {
//if (portId.getName().equals("/dev/term/a")) {
SimpleRead reader = new SimpleRead();
public SimpleRead() {
try {
serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);
} catch (PortInUseException e) {}
try {
inputStream = serialPort.getInputStream();
} catch (IOException e) {}
     try {
serialPort.addEventListener(this);
     } catch (TooManyListenersException e) {}
serialPort.notifyOnDataAvailable(true);
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
readThread = new Thread(this);
readThread.start();
public void run() {
try {
Thread.sleep(20000);
} catch (InterruptedException e) {}
public void serialEvent(SerialPortEvent event) {
switch(event.getEventType()) {
case SerialPortEvent.BI:
case SerialPortEvent.OE:
case SerialPortEvent.FE:
case SerialPortEvent.PE:
case SerialPortEvent.CD:
case SerialPortEvent.CTS:
case SerialPortEvent.DSR:
case SerialPortEvent.RI:
case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
break;
case SerialPortEvent.DATA_AVAILABLE:
byte[] readBuffer = new byte[20];
try {
while (inputStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
System.out.print(new String(readBuffer));
} catch (IOException e) {}
break;
Thanks a bunch!! :)
Jess...

Answer 1

I actually got my scanner to work. I got my SimpleRead.java to work as an application. I set up this as an applet. Now my problem is that I the inputread reading from the serial port is not reading correct data always. It sometimes does scan correct data at times and other times it will not. So, I am not sure what is wrong. Does anyone have any clue why this could happen?