Load and read data from Json file - dart

Question

I create simple app get data of marker from json file and draw them.
The code below is get data from data.json and add to the list of marker.
I got problem. I can't get data from json file and add it to my marker list. How can I do that?
My main.dart code
class MapSample extends StatefulWidget {
#override
State<MapSample> createState() => MapSampleState();
}
class MapSampleState extends State<MapSample> {
#override
void initState() {
var location = Location();
FutureBuilder(
future:
DefaultAssetBundle.of(context).loadString('assets/data.json'),
builder: (context, snapshot) {
// Decode the JSON
var new_data = json.decode(snapshot.data.toString());
for (var i = 0; i < new_data.length; i++) {
location = Location(
id: new_data[i]['id'],
lat: new_data[i]['x'],
long: new_data[i]['y'],
);
locations.add(location);
//print(location.lat);
}
});
super.initState();
}
}
My data.json
[{
"rownum": 1,
"id": "E3E0D2C5-CB82-4AF3-8D5D-4CD323560F59",
"x": 10.99803453,
"y": 106.65676933,
}, {
"rownum": 2,
"id": "5FFB6736-7D1F-4B40-A397-32EB3128BC30",
"x": 10.99793271,
"y": 106.65666751,
},

Answer 1

I think this is what you are looking for.
import 'package:flutter/material.dart';
import 'package:flutter/services.dart' show rootBundle;
void main() {
runApp(Test());
}
class Test extends StatefulWidget {
#override
_TestState createState() => _TestState();
}
class _TestState extends State<Test> {
Future _future;
List<Location> locations;
Future<String> loadJson() async =>
await rootBundle.loadString('assets/data.json');
#override
void initState() {
_future = loadJson();
super.initState();
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: FutureBuilder(
future: _future,
builder: (context, snapshot) {
if (snapshot.hasData) {
for (var v in snapshot.data) {
locations.add(Location(
id: v['id'],
lat: v['x'],
long: v['y'],
));
}
return Text(snapshot.data);
} else {
return CircularProgressIndicator();
}
}),
),
);
}
}
class Location {
final String id;
final double lat;
final double long;
Location({this.id, this.lat, this.long});
}

Answer 2

Try this.
You have to add the data.json file in assests.
Then add in to pubspec.yaml file.
assets:
- assets/data.json
Then add this below code.
String jsonData = await DefaultAssetBundle.of(context).loadString("assets/data.json");
final jsonResult = json.decode(jsonData);