I would like to refactor code which looks something like this:

String input; // input from client socket.
if (input.equals(x) {
  doX();
} else if (input.equals(y) {
  doY();
} else {
  unknown_command();
}

It is code which checks input from socket to perform some action, but I don't like the if else construction because every time a new command is added to the server (code) a new if else has to be added which is ugly. Also when deleting a command the if else has to be modified.