Flutter - 07. Stateful Widget Lifecycle

Understanding the lifecycle of Flutter Stateful widgets:

createState

• Called once when the widget is first created.
• Returns a State instance.

initState

• Called once immediately after the State is created.
• Used for variable initialization and subscribing to event streams.

build

• Called every time the widget needs to be rebuilt.
• Returns the widget's UI.

setState

• Called to notify the framework of state changes.
• Triggers a rebuild (the build method is called again).

didUpdateWidget

• Called when the widget configuration changes.
• Useful for reacting to changes from the parent widget.

deactivate

• Called when the widget is removed from the tree.
• Used for cleanup (unsubscribing from event streams).

dispose

• Called when the widget is permanently removed.
• Final cleanup — releasing resources.

Lifecycle example:

1. createState -> initState -> build -> setState -> build -> deactivate -> dispose