Java RMI server to client communication not working

Question

I'm developing a game which use server communication with socket and RMI. I'm quite new to RMI and i'm encountering some problems while trying to communicate between a server and a client which are not on the same PC. In localhost it work flawlessy, otherwise communication don't work as expected. Here some code snippets:

public RMIServer (ServerInterface mainServer){
    this.mainServer = mainServer;
}

public void startServer() throws IOException {
    Registry registry  = createOrLoadRegistry(Server.RMIPORT);
    try {
        System.out.println("Insert server ip address: ");
        Scanner in = new Scanner(System.in);
        String address = in.nextLine();
        in.close();
        System.setProperty("java.rmi.server.hostname", address);
        registry.bind("RMIServerInterface", this);
        UnicastRemoteObject.exportObject(this, Server.RMIPORT+1);
    } catch (RemoteException | AlreadyBoundException e) {
        System.err.println(e.getMessage());
    }
}    

private Registry createOrLoadRegistry(int port) throws IOException{
    try {
        System.out.println("creating register.. ");
        return LocateRegistry.createRegistry(port);
    } catch (RemoteException e) {
        System.err.println(e.getMessage());
    }
    try {
        return LocateRegistry.getRegistry(port);
    } catch (RemoteException e) {
        System.err.println(e.getMessage());
    }
    return null;
}

Socket works very good instead.

EDIT: To let RMI work in first place I was forced to use:

System.setProperty("java.rmi.server.hostname")

enter code here

because server IP was randomly set to 127.0.1.1 (loopback). I printed the stack track on server side and this was the result:

    creating register.. 
Insert server ip address: 
192.168.1.73
Socket server is ready
Recieved RMI client connection
create first room..
cchvo has been added to room
Number of players: 1
java.rmi.ConnectException: Connection refused to host: 127.0.1.1; nested exception is: 
  java.net.ConnectException: Connessione rifiutata (Connection refused)
  at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
  at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216)
  at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202)
  at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:130)
  at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:227)
  at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:179)
  at com.sun.proxy.$Proxy1.notifyNewPlayer(Unknown Source)
  at server.RMIPlayer.notifyNewPlayer(RMIPlayer.java:28)
  at server.Room.notifyNewPlayer(Room.java:147)
  at server.Room.addPlayer(Room.java:106)
  at server.Server.createRoom(Server.java:98)
  at server.Server.addPlayerFirstAvailableRoom(Server.java:119)
  at server.RMIServer.addRoom(RMIServer.java:82)
  at server.RMIServer.loginPlayer(RMIServer.java:75)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:346)
  at sun.rmi.transport.Transport$1.run(Transport.java:200)
  at sun.rmi.transport.Transport$1.run(Transport.java:197)
  at java.security.AccessController.doPrivileged(Native Method)
  at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
  at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
  at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
  at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:683)
  at java.security.AccessController.doPrivileged(Native Method)
  at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.ConnectException: Connessione rifiutata (Connection refused)
  at java.net.PlainSocketImpl.socketConnect(Native Method)
  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
  at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
  at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
  at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
  at java.net.Socket.connect(Socket.java:589)
  at java.net.Socket.connect(Socket.java:538)
  at java.net.Socket.<init>(Socket.java:434)
  at java.net.Socket.<init>(Socket.java:211)
  at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:40)
  at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:148)
  at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
  ... 30 more

Answer 1

You're doing everything in the wrong order.

1. Set java.rmi.server.hostname .
2. Export the remote object.
3. Create the Registry.
4. Bind the remote object to the Registry.

Answer 2

I've finally managed to fix this by simply adding

System.setProperty ("java.rmi.server.hostname", clientIp)

in client too. Hope to help someone with the same problems.

PS: only one PC (with Debian) over 3 had this problem with hostname, the others running Ubuntu and Windows had not. Thanks for the answers.