Either another application is already using the port or your application keeps on creating new instances of the ServerSocket. If you create a ServerSocket object for a specific port and then create another instance of it on the same port it will return a bind exception.

First see if your application is in a loop creating new instances of the ServerSocket. Then check with your sys admin whether or not the port is in use. Remember each client will open a socket to communicate with the server. The server will however have only one ServerSocket (on a specific port). It will then call 'accept' which will return a Socket object when it detects a client trying to connect.

Regards.