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Java Classpath

Lots of problems for new  and more experienced users with the classpath. See classpath.html for some info and hopefully it will solve your problems.

Java Serial CommAPI

Update Sept. 2008

Sun have dicontinued support of the Comm API for the  Windows platform.
A possible alternative is available at see:

Reference Material

A very good chapter on Java Serial comms  is available @  . This is from the book  "Programming Lego Mindstorms With Java" .

Another useful web site is  @

I've had some odd problems with the Java CommAPI.
Here are some pointers to a solution that worked for me.
[Running Win2K and [JDK] represent the directory path to the Java Development Kit eg [JDK] == c:\jdk1.4.1\]

Synopsis [For a full version with explanations  see here]
    Make sure that the PATH environment variable is written such that the '<JDK>\bin'directory is before the
    'c:\WINNT\system' directory  [This means that you know that this is the version of java that runs and not
    'java.exe' in c:\WINNT\system]
    In development (i.e. college) useful jar archives or java classes can be placed in the [JDK]\jre\lib\ext directory.
    This is atomatically searched by '<JDK>\bin\java.exe' before (!) any other location, even before those classes
    specified using the CLASSPATH environment variable or using the '-classpath' switch
    For production code to be really sure that you will see the required classes use the '-classpath' switch when running the JVM
    java –classpath C:\myapps\proj1\ MyApp
    For the CommAPI (Please note these are not the same as Sun's recommendations ... but it works :) )
            extract the ziped file you downloaded from Sun into some directory. Then find the files comm.jar, win32com.dll
            Copy the file 'win32com.dll' to the [JDK]\bin directory.
            Copy 'comm.jar' to [JDK]\jre\lib\ext directory
            Copy the file '' to the directory [JDK]\jre\lib.
 I also found the folowing at the Java Tech site [Note they do not  install to the <JDK>/lib or <JDK>/bin directories at all! ]

Installing javax.comm

The J2SE installation does not include the javax.comm set of files. You must download and install it separately. The Sun Java Communications site currently provides files suitable for Windows platforms and Solaris. See the resources section below for links to sites that provide javax.comm for Linux .

For example, for MS Windows follow this procedure:

  1. Download and unpack the file.
  2. Place the win32com.dll in j2sdk1.4.2\jre\bin directory (or the \jre\bin subdirectory of your current J2SDK directory.)
  3. Place the comm.jar in \jre\lib\ext.
  4. Place the in \jre\lib.
  5. Do not alter the CLASSPATH.


DOS Batch Files

A good introduction and advanced tutorial from Cay Horstmann is available. The intro gives you some basic info and the advanced shows you how to write batch files [a usefull skill]:



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