Welcom to Java,
You have to define the port of your choice having in mind that;
Port numbers in TCP/IP systems are 16-bit numbers and the values range
In practice, port numbers below 1024 are reserved for
predefined services, and you should not use them unless communicating
with one of those services (such as telnet, Simple Mail Transport
Protocol [SMTP] mail, ftp, and so on).
Client port numbers are allocated
by the host OS to something not in use, while server port numbers are
specified by the programmer, and are used to identify a particular service.
Note that for you to establish a communication,
Both client and server must agree in advance on which port to use. If the
port numbers used by the two parts of the system do not agree,
communication does not occur.