Why do you need to call setState (() }) in a stateful widget when changing some internal data )?

Calling setState notifies the framework that the internal state of this object has changed in a way that might impact the user interface in this subtree , which causes the framework to schedule a build for this State object.

The setState() method notifies the framework that the internal state of the current object is “dirty,” which means that it has been changed in a way that might impact the UI. After this notification, the framework will call the build() method to update and rebuild a widget.

The short answer is that just add currentIndex as one of the parameter inside your navBarSection . Inside home. dart , just pass the currentIndex of the page.

setState is a way to dynamically change the UI. We call it inside the State Object class of the StatefulWidget. Calling setState marks the corresponding Widget dirty .20 Haz 2021