How do I open a socket?

If you are programming a client, then you would open a socket like this:

Socket MyClient;
MyClient = new Socket("Machine name", PortNumber);

Where Machine name is the machine you are trying to open a connection to, and PortNumber is the port (a number) on which the server you are trying to connect to is running. When selecting a port number, you should note that port numbers between 0 and 1,023 are reserved for privileged users (that is, super user or root). These port numbers are reserved for standard services, such as email, FTP, and HTTP. When selecting a port number for your server, select one that is greater than 1,023!

In the example above, we didn't make use of exception handling, however, it is a good idea to handle exceptions. (From now on, all our code will handle exceptions!) The above can be written as:

Socket MyClient;
try {
MyClient = new Socket("Machine name", PortNumber);
}
catch (IOException e) {
System.out.println(e);
}

If you are programming a server, 
then this is how you open a socket:

ServerSocket MyService;
try {
MyServerice = new ServerSocket(PortNumber);
}
catch (IOException e) {
System.out.println(e);
}

When implementing a server you also need
to create a socket object from the ServerSocket
in order to listen for and accept connections
from clients.

Socket clientSocket = null;
try {
serviceSocket = MyService.accept();
}
catch (IOException e) {
System.out.println(e);
}