In what cases and how does the didUpdateWidget method get called in the widget lifecycle?

The didUpdateWidget method is called in the lifecycle of a StatefulWidget in Flutter when the parent widget updates the configuration of the current widget, meaning a new instance of the widget is created with new parameters, but the same State object is preserved.

This occurs after the build method and before the next render, allowing the State to compare the old and new widgets and update its internal state if necessary.

Example usage:

@override
void didUpdateWidget(covariant MyWidget oldWidget) {
  super.didUpdateWidget(oldWidget);
  if (widget.someValue != oldWidget.someValue) {
    // Update state in response to parameter change
    setState(() {
      // ...
    });
  }
}

Thus, didUpdateWidget is useful for reacting to changes in widget input parameters without recreating the State.