In Flutter, a stateful widget is a widget that has mutable state. This means that the widget’s state can change over time, and the widget needs to be rebuilt to reflect those changes in the user interface.
The lifecycle of a stateful widget is divided into several stages:
- Creation: When a stateful widget is created, the framework calls the
createStatemethod to create an instance of the widget’s state class. The state class is responsible for managing the widget’s state and building the widget’s user interface.
- Initialization: After the state class is created, the framework calls the
initStatemethod on the state object. This is a good place to perform one-time initialization tasks, such as allocating resources or setting up listeners.
- Build: Whenever the widget’s state changes, the framework calls the
buildmethod on the state object to rebuild the widget’s user interface. The
buildmethod should return a widget tree that reflects the current state of the widget.
- Update: If the parent widget rebuilds, the framework calls the
didUpdateWidgetmethod on the state object to give it a chance to update itself based on the new parent widget.
- Deactivation: When the stateful widget is removed from the tree, the framework calls the
deactivatemethod on the state object. This is a good place to perform cleanup tasks, such as releasing resources or canceling timers.
- Disposal: When the state object is no longer needed, the framework calls the
disposemethod to allow the state object to release any resources it is holding.
Here is a summary of the stateful widget lifecycle:
createStateis called when the widget is created.
initStateis called immediately after
buildis called whenever the widget’s state changes.
didUpdateWidgetis called if the parent widget rebuilds.
deactivateis called when the widget is removed from the tree.
disposeis called when the state object is no longer needed.
It’s important to understand the stateful widget lifecycle in order to create effective Flutter apps. By managing the widget’s state and resources correctly, you can create efficient and responsive user interfaces.