Is StatefulWidget immutable?

didUpdateWidget method Null safety key, the framework will update the widget property of this State object to refer to the new widget and then call this method with the previous widget as an argument . Override this method to respond when the widget changes (e.g., to start implicit animations).

According to the Flutter official docs, didChangeDependencies() is called when a dependency of the State object changes or immediately after initState() . It is safe to call BuildContext.

Overriding of initState() method performs initialization which depends on the location at which this object was inserted into the tree (like context) or on the widget used to configure this object (or widget). In simple terms, while a page in flutter gets created on screen, this method gets called at very first.29 Nis 2020

The @override annotation applies to instance methods, instance getters, instance setters and instance variables (fields) . When applied to an instance variable, it means that the variable’s implicit getter and setter (if any) are marked as overriding. It has no effect on the variable itself.

We generally override this method if we need to do some sort of initialisation work like registering a listener because, unlike build() , this method is called once. And to unregister your listener (or doing some post work), you override dispose() method.

Note that you can do it quickly by clicking on your widget and do (ctrl +) .