understanding some serial port code...

[vitroblue]

hello

i need to send and get one char from serial port
but i'm making a mess of it
so i kept reading a few tutorials in the web
in the end i dowloaded and tried a code i found,
it works
but this thing only sends one string and gets one string back, then closes all communication.
i need to leave the port open because i'll be receiving commands from a microcontroller. it is the micro the one who should say when to close the comunications
but in this code i can't find exactly how and why the port is closed
can you explain it to me?

first things first

//all this is quite clear

import java.io.*;
import java.util.*;
import gnu.io.*;

public class WriteReadSerial implements Runnable, SerialPortEventListener{
 static Enumeration portList;
 static CommPortIdentifier portId;
 static String messageString = "b";
 static SerialPort serialPort;
 static OutputStream outputStream;
 static InputStream inputStream;
 static boolean outputBufferEmptyFlag = false;
 Thread eventThread;

the main...

public static void main(String[] args) {
  boolean portFound = false;
  String  defaultPort = "/dev/term/a";
//I know args[] contains all arguments found when executing, but how comes the first argument is a port by default?
//anyways here they store it
  if (args.length > 0) {
      defaultPort = args[0];
  } 
//why are they doing this?
  WriteReadSerial puertoSerial = new WriteReadSerial();

//here, it is reading from console? it is not the serial port, right?
  try{
   BufferedReader br = new BufferedReader(new  InputStreamReader(System.in));
   String linea = br.readLine();

//this is the port clossing, i guess 
  puertoSerial.closeSerialP();
   System.out.println(linea); 
  }catch(Exception e){
   e.printStackTrace(); puertoSerial.closeSerialP();
  }
 }

then, somewhere else in the class, there's this

static void closeSerialP(){
  try{
   Thread.sleep(2000); // Be sure data is xferred before closing
  }catch (Exception e)
  {System.out.println(e.toString());}

//THIS IS THE CLOSURE
  serialPort.close();
  System.out.println("Puerto cerrado...");
  System.exit(1);
 }

So
what should i do?
delete the call to this method in the previous one and instead place the call in the method that process the microcontroller orders?

other thing i dont understand is: i dont see calls to the reading and writing because in the rest of the code, that is done by event. so why is the port being closed there?

thank you

[moutanna]

Check on this link

http://java.sun.com/developer/Books/javaprogramming/cookbook/11.pdf

hope it helps

[vitroblue]

Check on this link

http://java.sun.com/developer/Books/javaprogramming/cookbook/11.pdf

hope it helps

oh, my
that code there is even more complex than mine
using gui just makes undestanding worse
why do i care about parallel ports there?
no parallel ports, no gui...
wow, i didn't know a class Frame existed...
i'll stay with byte[]

aaahh... this high level programming is driving me nuts

well nevermind - half - my previous post, i undestood already where and how is the port open. but it seems this thing transmits a message as soon as the port is ready, that's why it closes right away in the main. but i have another doubt there

boolean openSerialP(){
  portList = CommPortIdentifier.getPortIdentifiers();
  while (portList.hasMoreElements()){
   portId = (CommPortIdentifier)portList.nextElement();
   if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL){
    String nombre = portId.getName();
    if (!(nombre.equals("COM3"))){
     System.out.println("ENTRANDO AL IF QUE COMPARA EL COM3..." + nombre);
     System.out.println(portId.getName()  +  " - " +  getPortTypeName(portId.getPortType()));

     try{
      serialPort = (SerialPort)portId.open("Read/Write", 2000); 
     }catch (PortInUseException e){
      System.out.println("Port in use.");
      System.out.println(e.toString());
     }

     try{
      outputStream = serialPort.getOutputStream();
      inputStream = serialPort.getInputStream();
     }catch (IOException e)
     {System.out.println(e.toString());}

     try{
        serialPort.addEventListener(this);
     } catch (TooManyListenersException e) 
     {System.out.println(e.toString());}

     try{
      serialPort.notifyOnDataAvailable(true);
      serialPort.notifyOnOutputEmpty(true);
     }catch (Exception e){
      System.out.println("Error setting event notification");
      System.out.println(e.toString());
      System.exit(-1);
     }

     try{
      serialPort.setSerialPortParams(9600, SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
     }catch (UnsupportedCommOperationException e)
     {System.out.println(e.toString());}



//since the sending starts here...


     eventThread = new Thread(this);
     eventThread.start();
     System.out.println("writing \""+messageString+"\" to " +serialPort.getName());

     try{
      outputStream.write(messageString.getBytes());
     }catch (IOException e)
      {System.out.println(e.toString());}
     break;
    }


// how do i take it out to a method i can call from any other random part - let's make that "main" - of the code?

/* would it be something like this?

public void writingS(String stuff){
     eventThread = new Thread(this);
     eventThread.start();
     System.out.println("writing \""+stuff+"\" to " +serialPort.getName());

     try{
      outputStream.write(stuff.getBytes());
     }catch (IOException e)
      {System.out.println(e.toString());}
}


*/

   }
  }
  return (true);
 }

PLEASE HELP