Pass by reference problem in RMI? [duplicate]

Answer 1

As answered by Ernest Friedman-Hill at link texthttp://www.coderanch.com/t/508960/java/java/pass-reference:

The root of problem was the fact that RMI doesn't support pass by reference , so making the message class serializable and creating the remote instance of ServerServices in that serializable class can make this application work

OR

creating the remote instance of Message class in client class and publishing that from RMI registry can also work.

In this code the local references were used instead of remote, so it was getting the 0 elements in the list from Serverservices class.

thanks again to: Ernest Friedman-Hill.

Answer 2

Change

private List<TTTClientRemote> serverList;

To:

private List<TTTClientRemote> serverList = new ArrayList<TTTClientRemote>();

Or initialize it somewhere before the for() in updateClients();

Answer 3

your question is not clear enough but:

debug your code, or put some logs (simply System.out.println) before the line that you are getting NPE. maybe you List is still null.

public void updateClients() throws RemoteException {
    **if (serverList != null) {**
        for (TTTClientRemote aClient : serverList) {
           aClient.updateClients("slam");
        }
    }
}