CODEWITHSUNDEEP
flutter
marielle
marielle

Reputation: 438

Widget is null inside initState

It's the first time a use Flutter (2.8.1) and I'having problems trying to undestrand what's going wrong.

I have a Stateful widget like this:

class SimpleWidget extends StatefulWidget {
  final Type2 aValue;
  const SimpleWidget({Key key, @required this.aValue}) : super(key: key);
  @override
  _SimpleWidgetState createState() => _SimpleWidgetState();
}

class _SimpleWidgetState extends State<SimpleWidget> {
  Type1 color;

  @override
  void initState() {
    super.initState();

    color = widget.aValue; // <-- widget is null
  }
  ...
}

that I call in this way:

List<Type1> something = await showDialog(
  context: context,
  builder: (context) {
    print('currentElement.aValue: ${currentElement.aValue}'); // not null
    return SimpleWidget(aValue: currentElement.aValue);
  },
);

Why is widget.aValue == null in initState()? How can I solve it?

Upvotes: 0

Views: 121

Answers (1)

Sam Chan
Sam Chan

Reputation: 1762

There are some error in your coding; The first one is construction of SimpleWidget

const SimpleWidget({Key key, @required this.aValue}) : super(key: key);

when you call like SimpleWidget(aValue: currentElement.aValue); It will should error like key can not be null. You can use ? to make it nullable. Also, @ should be remove, it is a syntax error

The correct one looks like

const SimpleWidget({Key? key, required this.aValue}) : super(key: key);

The second one is in SimpleWidgetState

You can change Type1 color; to late Type1 color; Or make it nullable. For more details, you can check flutter codelabs

Upvotes: 1

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