StatefulElement constructor
- StatefulWidget widget
Creates an element that uses the given widget as its configuration.
Implementation
StatefulElement(StatefulWidget widget)
: _state = widget.createState(),
super(widget) {
assert(() {
if (!state._debugTypesAreRight(widget)) {
throw FlutterError.fromParts(<DiagnosticsNode>[
ErrorSummary('StatefulWidget.createState must return a subtype of State<${widget.runtimeType}>'),
ErrorDescription(
'The createState function for ${widget.runtimeType} returned a state '
'of type ${state.runtimeType}, which is not a subtype of '
'State<${widget.runtimeType}>, violating the contract for createState.',
),
]);
}
return true;
}());
assert(state._element == null);
state._element = this;
assert(
state._widget == null,
'The createState function for $widget returned an old or invalid state '
'instance: ${state._widget}, which is not null, violating the contract '
'for createState.',
);
state._widget = widget;
assert(state._debugLifecycleState == _StateLifecycle.created);
}