Sounds like you haven't set the JAVA_HOME environment variable. This should point to the install location of your JDK - e.g. d:\j2sdk1.4.1
When you start JBoss up, either thru run.bat or run.sh (depending upon whether you're on Windows or something else), one of the things it'll do is use JAVA_HOME to add the tools.jar library to the application classpath. This contains the Java compiler classes, including sun.tools.javac.Main
thanks man, it worked...