The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases.
You can enable debugging messages by using the -Dcom.sun.sdp.debug flag. If you specify a file, the messages will be output to that file. Otherwise, the messages will be printed to standard output.
This first example shows sample messages printed to standard output:
% java -Dcom.sun.sdp.conf=sdp.conf -Dcom.sun.sdp.debug ExampleApplicaton BIND to 192.0.2.1:5000 (socket converted to SDP protocol) CONNECT to 129.156.232.160:80 (no match) CONNECT to 192.0.2.2:80 (socket converted to SDP protocol)
This second example shows the output redirected to a file named debug.log:
% java -Dcom.sun.sdp.conf=sdp.conf -Dcom.sun.sdp.debug=debug.log ExampleApplication [1] 27310 % tail -f debug.log BIND to 192.0.2.1:5000 (socket converted to SDP protocol)