private static final 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);
	context.renderResponse();
    }