private static String US = "United States";
   ...
       public void countryChanged(ValueChangeEvent event) {
           FacesContext context = FacesContext.getCurrentInstance();
           if (US.equals((String) event.getNewValue()))
               context.getViewRoot().setLocale(Locale.US);
           else
               context.getViewRoot().setLocale(Locale.CANADA);
       }
   }