My services file (C:\\WINDOWS\\system32\\drivers\\etc\\services) has a bunch of Port to Service mappings:
echo 7/tcp
echo 7/udp
What you are looking for is a Java implementation of the Linux getservbyport()
system call. Take a look at http://github.com/wmeissner/jnr-netdb. Also, do a Google search for java getservbyport
I don't think there is some API in java for this purpose. You will either need to parse this file or maintain port service mapping in some form (Properties file,db etc.). example to parse from system file is :
http://www.javafaq.nu/java-example-code-162.html