如何加载提供者列表 flutter

Question

I want to how to load saved list data on new dart file with provider.

The below code is my list with provider.

'items' list will be added with integer items.

class ListProvider is in provider.dart file.

and

Swapping function is in different dart file.

How can Swapping use added data in 'items' list??

class ListProvider with ChangeNotifier {
  List<int> items = [
    -1,
  ];

  void addItem(int item) {
    items.add(item);
    notifyListeners();
  }

  bool contains(int item) {
    bool answer = items.contains(item);
    return answer;
  }
}

IconButton(
                  onPressed: Swapping,
                  icon: Image.asset('assets/refresh.png'),
                  iconSize: 20,
                ),


Swapping() {
    Random random = new Random();
    var numberHats = random.nextInt(items.length);
    setState(() {
      hat = hat_items[items[numberHats]];
    });
  }

Answer 1

if you use provider you not should use setState you need to ChangeNotifierProvider Widget

     ChangeNotifierProvider(
          create: (context) => ListProvider(),
          child: Scaffold(
child:....
child:IconButton(
                  onPressed: Swapping,
                  icon: Image.asset('assets/refresh.png'),
                  iconSize: 20,
                ),
),
        ),

and edit your model change with keyword to extends in Model

class ListProvider extends ChangeNotifier 

more details check enter link description here