PortInUse Exception in SerialDemo


 
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# 8  
Old 12-04-2012
I'm not worried about someone changing any binaries (unless that someone is me). It's a demo box and I'm the only one on it.

Excuse my ignorance, but I'm a windows guy and my unix person is out all week.
How do I know what user/group us running the JVM?
I did a ps -ef but did not see anything java related.

Thanks.
# 9  
Old 12-04-2012
The person who corrupts the java binary by accident could easily be you. The sooner you get over this habit the better -- 777 is not the magic sledgehammer to fix all permissions problems, it's dumb, and dangerous.

Try running a java program then seeing if you see the JVM in ps.
# 10  
Old 12-04-2012
I think its not an issue of what permissions are set on java binary but an issue of what permissions are set on the serial device.
# 11  
Old 12-04-2012
That already appears to be 666, should not be a problem.

But java is an odd language with only threads, subject to contention within itself when it tries to use real system resources.
# 12  
Old 12-04-2012
I promise to never use 777 willy-nilly again.
I ran the SerialDemo and the only thing I see using ps is 'java SerialDemo'. I do not see the JVM or any other java process.
# 13  
Old 12-04-2012
Can we see the code for the serial demo? Perhaps it does something odd like try to open the device twice. The behavior of that would be potentially different on different platforms.
# 14  
Old 12-04-2012
I'm pretty sure it's not the SerialDemo code as I have created a very simple app that does nothing but scroll through the list of ports and attempt to open them.
Here's the code (hand-typed so excuse the typos):

Code:
import javax.comm.*;
import java.util.Enumeration;
public class Main {
  public Main() {
  }
  public static void main(String[] args) {
    try {
      Enumeration portList = CommPortIdentifier.getPortIdentifiers();
      while(portList.hasMoreElements()){
        CommPortIdentifier pi = (CommPortIdentifier)portList.nextElement();
        try {
          SerialPort sp = (SerialPort)pi.open("TEST", 5000);
        } catch(PortInUseException piue) {
          System.out.println("Port In Use");
        }
      }
    } catch(Exception e) {
      System.out.println(e.getMessage());
    }
  }
}


Last edited by Scott; 12-04-2012 at 01:08 PM.. Reason: Please use code tags
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