@Nullable
    public Controller getController(int position) {
        String instanceId = visiblePageIds.get(position);
        if (instanceId != null) {
            return host.getRouter().getControllerWithInstanceId(instanceId);
        } else {
            return null;
        }
    }
@ Nullable public Controller getController ( int position ) { String instanceId = visiblePageIds . get ( position ) ; if ( instanceId != null ) { return host . getRouter ( ) . getControllerWithInstanceId ( instanceId ) ; } else { return null ; } }
Returns the already instantiated Controller in the specified position or {@code null} if
this position does not yet have a controller.