main.dart

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

class _MyHomePageState extends State<MyHomePage> {

  List<DataPoint> timeline = List<DataPoint>();
  
    void loadData(){
      setState(() {
        jsonResponse = jsonResponse['timelineitems'][0];
       // print(jsonResponse);

        jsonResponse.forEach((key, val){
          if(key != 'stat'){
            //print(key);
            //print(val['total_cases']);
            timeline.add(DataPoint(key, val['total_cases']));
          }
        });
        
        print(timeline.length);
        print("\n\n");
        //print(timeline);
      });
    } 


    @override
  void initState() {
    super.initState();
    CallAPI.getData(loadData);
  }

  @override
  Widget build(BuildContext context) {

    if(jsonResponse == null){
      return Scaffold(
        appBar: AppBar(
          title: Center(
            child: Text(
              'CoronaVirus Tracker',
            ),
          ),
          backgroundColor: Colors.purple,
          actions: <Widget>[
            Padding(
              padding: const EdgeInsets.all(16.0),
              child: InkWell(
                child: Icon(Icons.show_chart, color: Colors.white,),
                onTap: (){},
                splashColor: Colors.red,
              ),
            ),
          ],
        ),
        body: Center(child: Text('Loading Data...'),),
      );
    }
    else{
      return Scaffold(
        appBar: AppBar(
          title: Center(
            child: Text(
              'CoronaVirus Tracker',
            ),
          ),
          backgroundColor: Colors.purple,
          actions: <Widget>[
            Padding(
              padding: const EdgeInsets.all(16.0),
              child: InkWell(
                child: Icon(Icons.show_chart, color: Colors.white,),
                onTap: (){
                  Navigator.pushNamed(context, '/graph', arguments: timeline);
                },
                splashColor: Colors.red,
              ),
            ),
          ],
        ),
        body: ShowListView(timeline),
      );
    }
  }
}