Java Programming

Hi! I have RxTx installed on my iMac with a usb-serial adapter.
I have managed to list all the available serial devices on the computer with this code:

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


public class FindPorts {
   
    public static void main(String[] args) {
Enumeration portList = CommPortIdentifier.getPortIdentifiers();
   while (portList.hasMoreElements()) {
   CommPortIdentifier portId = (CommPortIdentifier)portList.nextElement();
   if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL){
   System.out.println(portId.getName() + " " +portId.getCurrentOwner());
   } 
   }


    }
}

The result I get in "Terminal" when I compile and run is:




Experimental: JNI_OnLoad called.
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7
/dev/tty.UC-232AC null
/dev/cu.UC-232AC null


So the computer found my usb-serial adapter /dev/tty.UC-232AC null & /dev/cu.UC-232AC null


The problem is when I try to write something to the port with this code:

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


public class SimpleWrite {
    static Enumeration      portList;
    static CommPortIdentifier portId;
    static String      messageString = "Hello, world!";
    static SerialPort      serialPort;
    static OutputStream       outputStream;
    static boolean      outputBufferEmptyFlag = false;
    
    public static void main(String[] args) {
boolean portFound = false;
String  defaultPort = "/dev/tty.UC-232AC";




if (args.length > 0) {
   defaultPort = args[0];
} 


portList = CommPortIdentifier.getPortIdentifiers();


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


   if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {


if (portId.getName().equals(defaultPort)) {
   System.out.println("Found port " + defaultPort);


   portFound = true;


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


continue;
   } 


   try {
outputStream = serialPort.getOutputStream();
   } catch (IOException e) {}


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


   try {
    serialPort.notifyOnOutputEmpty(true);
   } catch (Exception e) {
System.out.println("Error setting event notification");
System.out.println(e.toString());
System.exit(-1);
   }
   
   
   System.out.println(
    "Writing \""+messageString+"\" to "
+serialPort.getName());


   try {
outputStream.write(messageString.getBytes());
   } catch (IOException e) {}


   try {
      Thread.sleep(2000);  // Be sure data is xferred before closing
   } catch (Exception e) {}
   serialPort.close();
   System.exit(1);
} 
   } 
} 


if (!portFound) {
   System.out.println("port " + defaultPort + " not found.");
} 
    } 




}

Terminal answers with:




Experimental: JNI_OnLoad called.
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7
Found port /dev/tty.UC-232AC
Port in use.


My usb-serial adapter is not connected to anything at the time when I run the program.. What does "Port in use" mean in this case?
And which one of /dev/tty.UC-232AC & /dev/cu.UC-232AC should I use in my program?




regards / Christian