class Data {
  late String data1;
  late String data2;

  String toJson() {
    return '{"data1":' + data1 + ',' + '"data2": ' + data2 + '}';
  }
}

class DataFetcher {
  Data getData() {
    var data = new Data();
    data.data1 = 'data1';
    data.data2 = 'data2';
    return data;
  }
}

void getData(SendPort sendPort) {
  var data = DataFetcher().getData();
  sendPort.send(data.toJson());
}

void getDataAsync() async {
  var receivePort= ReceivePort(); //port for isolate to receive messages.
  var isolate = await Isolate.spawn(getData, receivePort.sendPort);
  receivePort.listen((data) {
    stdout.write('Receiving: ' + data + ', ');
    isolate.kill();
  });
}

void main(){
  getDataAsync();
}