java - "ClassCastException: $Proxy0 cannot be cast" error while creating simple RMI application -

i creating first, simple rmi client-server application.

here code:

interface "icommunication"

package itu.exercies.rmi.server;      import java.rmi.remote;     import java.rmi.remoteexception;  public interface icommunication extends remote   {     public string docommunicate(string name) throws remoteexception;   } 

interface implementation "communicationimpl":

package itu.exercies.rmi.server;  import java.rmi.remoteexception; import java.rmi.server.unicastremoteobject;  public class communicationimpl extends unicastremoteobject implements icommunication {      /**      *       */     private static final long serialversionuid = 1l;      public communicationimpl() throws remoteexception {         super();      }      @override     public string docommunicate(string name) throws remoteexception {          return "hello server , whats " +name+ " ?!\n";     }  } 

here main class of server "communicationserver":

package itu.exercies.rmi.server;  import java.net.malformedurlexception; import java.rmi.naming; import java.rmi.remoteexception;   public class communicationserver {     /**      * @param args      * @throws remoteexception       * @throws malformedurlexception       */     public static void main(string[] args) throws remoteexception, malformedurlexception {         communicationimpl imp = new communicationimpl();         naming.rebind("communicationimpl", imp);         system.out.println("server started...");         system.out.println("object registered. bound name 'communicationimpl'.");      }  } 

and client "communicationclient":

package itu.exercies.rmi.client;  import java.net.malformedurlexception; import java.rmi.naming; import java.rmi.notboundexception; import java.rmi.remoteexception;  import itu.exercies.rmi.server.communicationimpl;  public class communicationclient {     public static void main(string[] args) throws malformedurlexception, remoteexception, notboundexception {          string url = new string("rmi://localhost/communicationimpl");         communicationimpl comm = (communicationimpl)naming.lookup(url);         string reply = comm.docommunicate("wiktor");         system.out.println(reply);       }  } 

now when try run it:

1. i navigate bin directory of project using terminal
2. i run rmiregistry there
3. i run communicationserver new terminal window (and prints out messages seems work)
4. i open third terminal window , when try run communicationclient throws exception.

java itu.exercies.rmi.client.communicationclientexception in thread "main" java.lang.classcastexception: $proxy0 cannot cast itu.exercies.rmi.server.communicationimpl @ itu.exercies.rmi.client.communicationclient.main(communicationclient.java:14)

so far have tried fix creating stub of 'communicationimpl' object using rmic instead of '$proxy0' error refers 'communicationimpl_stub':

exception in thread "main" java.lang.classcastexception: itu.exercies.rmi.server.communicationimpl_stub cannot cast itu.exercies.rmi.server.communicationimpl @ itu.exercies.rmi.client.communicationclient.main(communicationclient.java:14)

at point have no idea errors. can give me suggestions?

replace

communicationimpl comm = (communicationimpl) naming.lookup(url); 

with

icommunication comm = (icommunication) naming.lookup(url); 

communicationimpl server implementation of icommunication. client neither knows nor cares implementation, interface.