i couldnt find a doc explaining how to compile,
i am new to java, so could you please share a doc how to compile these sources
You can download the jar of compiled classes to save yourself from having to compile the sources if you want. Otherwise, compilation is really just a matter of running javac (making sure seroUtils.jar is in your classpath). If you don't understand this it's because you are new to Java. Once you understand Java compilation, building BACnet4J will be trivial. You might also look into ANT too.