Re: mvc design doubts

thanks a lot for the suggestions..
I modified the classes accordingly.

class BasicModel implements Observable{
    public Result processInputs(String decimalInput,File selectedFile)
{
        Result result;
        doSomeWork(selectedFile,decimalInput);
        result=makeResult();
        return result;
    }
    public void doSomeWork(selectedFile,decimalInput){
        try{
        //process the data
        ...
        }catch(SomeException e){
            String response="specific message"+e.getMessage();
            setChanged();
            notifyObservers();

        }
    }
    ...
}

class ErrorHandler implements Observable{
    private BasicView view;
    public ErrorHandler(BasicView v){
        view=v;
    }
    public void update (Observable obj, Object arg) {
        if (arg instanceof String) {
            resp = (String) arg;
            view.displayMessage(resp);
        }
    }
    ...
}

class Controller{
    private BasicView view;
    private BasicModel model;
    private SimpleUIValidator sValidator;
    private StringBuilder errorMsg;
    private ErrorHandler errorhandler;
    public Controller(BasicView v,BasicModel m){
        view=v;
        view.addOKButtonListener(new SimpleButtonListener());
        model=m;
        errorhandler=ErrorHandler(view);
        model.addObserver(errorhandler);

    }
    ...
}