Having trouble with ServerSocket

I am trying to do the tutorial at oracle.com for sockets. I have written the sample server program and I am trying to test it out. I am getting this error:

Could not listen on port: 1313
Exception in thread "main" java.lang.NullPointerException
at com.newera.backbone.OpenEars.main(OpenEars.java:25 )

from this part of code:

Code:

---

try {
                serverSocket = new ServerSocket(1313);
        } catch (IOException e) {
                System.out.println("Could not listen on port: 1313");
        }
       
        Socket clientSocket = null;
       
        try {
                clientSocket = serverSocket.accept();
        } catch (IOException e) {
                System.out.println("Failed to Accept Connection");
                System.exit(-1);
        }

---

I have tried a bunch of different ports, so I'm confident that the port is not already occupied. I am testing this on my desktop computer and not a dedicated server (not finished setting it up), could this possibly be the cause? I don't think it should be, as all I am trying to do is listen to a port. Then again, I don't really know all that much about ports and sockets, so... Any help will be appreciated.

Ok, never mind. In case anyone else ever has this problem, make sure that a previous run of the program isn't already listening on the port in question. Stupid mistake on my part..