TypeError（类型'String'不是'index'类型'int'的子类型）

Question

This my Code. When i run code i'm getting a error like this
"TypeError (type 'String' is not a subtype of type 'int' of 'index')". Is it something Do with Json Data or the I'm using Wrong Data Type. Does Future<List<Arrivals>> is written correctly?

    class MyHomePage extends StatefulWidget {
      @override
      _MyHomePageState createState() => _MyHomePageState();
    }

    class _MyHomePageState extends State<MyHomePage> {
      List<Arrivals> details = [];
      Future<List<Arrivals>> _getDetails() async {
        var data =
            await http.get("https://flight-api-maldives.herokuapp.com/arrivals");
        var jsonData = jsonDecode(data.body);

        for (var val in jsonData) {
          Arrivals arrivals = Arrivals(
            val['Scheduled'],
            val['Revised'],
            val['From'],
            val['Flight'],
            val['Status'],
          );
          details.add(arrivals);
          print(details.length);
        }
        return details;
      }

      @override
      Widget build(BuildContext context) {
        return Scaffold(
          body: SingleChildScrollView(
            child: Column(
              children: <Widget>[
                FutureBuilder(
                  future: _getDetails(),
                  builder: (BuildContext context, AsyncSnapshot snapshot) {
                    if (snapshot.data != null) {
                      return Container(
                        child: ListView.builder(
                          itemBuilder: (BuildContext context, int index) {
                            return Center(child: Text('snapshot.data[index].Scheduled'),);
                          }
                        ),
                      );
                    }else{
                       return Center(
                        child: Text('NO'),
                      );
                    }
                  },
                )
              ],
            ),
          ),
        );
      }
    } 
    class Arrivals {
      final String Scheduled;
      final String Revised;
      final String From;
      final String Flight;
      final String Status;

      Arrivals(this.Scheduled, this.Revised, this.From, this.Flight, this.Status);
    }

this is the json data im using:

[
  [
    {
      "Scheduled": "06:35",
      "Revised": "06:35",
      "From": "Kaadedhdhoo (KDM)",
      "Flight": "Maldivian Q2 149",
      "Status": "On-Time"
    },
    {
      "Scheduled": "06:40",
      "Revised": "06:40",
      "From": "Dharavandhoo Island (DRV)",
      "Flight": "Maldivian Q2 289",
      "Status": "On-Time"
    },
 ]
]

Where is the picture of my error https://i.stack.imgur.com/qVWLc.png

Answer 1

the main problem is in json. it is list of list.

 var jsonData = jsonDecode(data.body);
    jsonData = jsonData[0]; // added line
    for (var val in jsonData) {

Moreover their is no need of so many extra code to just display list view you can use following simple code to display list view. In addition to that Listview.builder require item count property to specify total number of item.

Replace below build method with your will work for you.

 @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder(
        future: _getDetails(),
        builder: (BuildContext context, AsyncSnapshot snapshot) {
          print(snapshot);
          if (snapshot.data != null) {
            return ListView.builder(
                itemCount: snapshot.data.length,
                itemBuilder: (BuildContext context, int index) {
                  return Center(
                    child: Text(snapshot.data[index].Scheduled.toString()),
                  );
                });
          } else {
            return Center(
              child: Text('NO'),
            );
          }
        },
      ),
    );
  }

Answer 2

In the JSON data, you've got a list inside a list.

val['Scheduled'],

This line is getting called on a list, so the square brackets are expecting an index rather than a map key