Explain the StatefulWidget lifecycle.

Updated Apr 28, 2026

Short answer

The lifecycle includes initState, didChangeDependencies, build, didUpdateWidget, and dispose.

createState(): Creates the State object.
initState(): Called once when inserted into the tree. Used for initialization.
didChangeDependencies(): Called after initState and whenever an inherited widget dependency changes.
build(): Called frequently to render UI.
didUpdateWidget(): Called if the parent rebuilds and provides a new widget instance to this State.
dispose(): Called when the widget is permanently removed from the tree. Used for cleanup.

Initializing an AnimationController in initState and cleaning it up in dispose to prevent memory leaks.

Calling `setState` inside `initState()`, which is redundant, or performing heavy async work directly in `dispose()`.