Java program to list all available serial ports in PC

How to list all available ports in a PC using Java

Some theory…

Java "Virtual Machine" doesn't support communication to support for serial and parallel ports with its default installation. So, if you want to access the serial (RS232) or parallel port with JAVA, you need to install a platform/operating system dependent library. The javax.comm from SUN enables programmers to write Java software that accesses communications ports in a platform-independent way. But Sun has discontinued the old Java comm. Package for Windows. The substitute is RXTX. RXTX will support all type of platforms including Windows, Linux, Mac OS X.

  

RXTX Installation procedure for Windows

• Download the zip file (rxtx-*-win32.zip) from the link,  http://rxtx.qbang.org/wiki/index.php/Download 
• Unzip rxtx-*-win32.zip 
• Zipped file contains 3 files - rxtxSerial.dll,rxtxParallel.dll and RXTXcomm.jar: 
• Copy rxtxSerial.dll and rxtxParallel.dll to JAVA_HOME\bin 
• (JAVA_HOME is the folder where JRE is installed on your system; e.g. c:\Program Files\Java\ jre1.6.0_03) 
• Copy RXTXcomm.jar to JAVA_HOME\lib\ext

Once installed, the IDE will need to know where to look for these installed files.  Even though the files exist in the JRE directory, each project needs to know about these files. 

The package of all the classes is gnu.io.

So in source code, instead of  import javax.comm.CommPortIdentifier, you have to use

import gnu.io.CommPortIdentifier.

My aim is to list all the available serial ports in my PC through Java.

import gnu.io.CommPortIdentifier;

import java.util.Enumeration;

import java.util.Vector;

/*
 * Get list of ports available on this particular computer
 */

public class ListSerialPorts

{

            public static void main(String[] args)

            {

                        int totalElements;

                        CommPortIdentifier portId;

                        Enumeration en = CommPortIdentifier.getPortIdentifiers();

                        Vector listData = new Vector(8);

                        // Walk through the list of port identifiers and, if it
                               // is a serial port, add its name to the list.

                        while (en.hasMoreElements())

                        {

                                    portId = (CommPortIdentifier) en.nextElement();

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

                                    {

                                                listData.addElement(portId.getName());

                                    }

                        }

                        totalElements = listData.size();

                       

                        //Iterate through the vector

                        for (int index = 0; index < totalElements; index ++)

                        {

                                    System.out.println(listData.get(index));

                        }

            }

}

While trying to run the program in Netbeans 7.0, it throws the error,

java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path thrown while loading gnu.io.RXTXCommDriver

Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path

            at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1682)

            at java.lang.Runtime.loadLibrary0(Runtime.java:823)

            at java.lang.System.loadLibrary(System.java:1030)

            at gnu.io.CommPortIdentifier.(CommPortIdentifier.java:83)

            at ListSerialPorts.main(ListSerialPorts.java:16)

Java Result: 1

Solution:-

Right Click ProjectName à Properties à Libraries à Add Jar à Select RXTXcomm.jar from the path C:\Program Files\Java\jre1.6.0_03\lib\ext\

Run the project.

It again throws exception,

java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path thrown while loading gnu.io.RXTXCommDriver

Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path

            at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1682)

            at java.lang.Runtime.loadLibrary0(Runtime.java:823)

            at java.lang.System.loadLibrary(System.java:1030)

            at gnu.io.CommPortIdentifier.(CommPortIdentifier.java:83)

            at ListSerialPorts.main(ListSerialPorts.java:16)

Java Result: 1

Solution:-

Copy rxtxSerial.dll and rxtxParallel.dll files to the root directory of your project

The output will be displayed as

Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version   = RXTX-2.1-7
COM1

Source:-

http://www.jcontrol.org/download/rxtx_en.html

http://rxtx.qbang.org/wiki/index.php/FAQ

http://mho.republika.pl/java/comm/