didUpdateWidget<Page> method
Called whenever the widget configuration changes.
If the parent widget rebuilds and request that this location in the tree
update to display a new widget with the same runtimeType and
Widget.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).
The framework always calls build
after calling didUpdateWidget, which
means any calls to setState
in didUpdateWidget are redundant.
If a State's build
method depends on an object that can itself
change state, for example a ChangeNotifier or Stream, or some
other object to which one can subscribe to receive notifications, then
be sure to subscribe and unsubscribe properly in initState,
didUpdateWidget, and dispose:
- In initState, subscribe to the object.
- In didUpdateWidget unsubscribe from the old object and subscribe to the new one if the updated widget configuration requires replacing the object.
- In dispose, unsubscribe from the object.
Implementations of this method should start with a call to the inherited
method, as in super.didUpdateWidget(oldWidget)
.
Implementation
void didUpdateWidget<Page>(
BuildContext context, Page oldWidget, Page widget) {}