update method

  1. @mustCallSuper
void update (covariant Widget newWidget)
@mustCallSuper

Change the widget used to configure this element.

The framework calls this function when the parent wishes to use a different widget to configure this element. The new widget is guaranteed to have the same runtimeType as the old widget.

This function is called only during the "active" lifecycle state.

Implementation 

@mustCallSuper
void update(covariant Widget newWidget) {
  // This code is hot when hot reloading, so we try to
  // only call _AssertionError._evaluateAssertion once.
  assert(_debugLifecycleState == _ElementLifecycle.active
      && widget != null
      && newWidget != null
      && newWidget != widget
      && depth != null
      && _active
      && Widget.canUpdate(widget, newWidget));
  _widget = newWidget;
}