StatefulWidget LifeCycle

 Flutter Lecture

Lifecycle of a Stateful Widget

A stateful widget in Flutter is a component that can maintain state and update

its appearance in response to changes. The lifecycle of a stateful widget

consists of a series of methods that are invoked at different stages of its

existence.

Overview

First, let’s have an overview of the stages in the lifecycle of a stateful widget, and

which method is invoked at which stage of the lifecycle.

1. createState(): Upon creation of the stateful widget, its constructor is

called, which initialises the widget. The createState() method is then

invoked, which creates the state object for the widget.

2. initState: This method is called after the widget is inserted into the widget

tree, when the object is created for the first time.

3. didChangeDependencies: This method is called when a dependency of

this widget changes. It is useful when the widget depends on some

external data or inherits data from its parent widget. It is also called

immediately after initState().

4. build: Builds the widget’s user interface based on its current state. This

method is called initially when the widget is first inserted into the widget

tree, and may be called repeatedly during the lifecycle whenever the

widget needs to be rebuilt.

5. setState: Triggers a rebuild of the widget when the state changes and the

associated methods are called again.

6. didUpdateWidget: Triggered when the widget is rebuilt with updated

properties. It is called after build() and allows you to compare the

previous and current widget properties.

7. deactivate: Called when the widget is removed from the tree but might be

inserted again.

8. dispose: Called when the widget is removed from the widget tree

permanently, allowing you to release resources held by the widget.

9. reassemble: Called when the application is reassembled during hot

reload.


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