在类之间传递日期（变量）？

Question

我需要在类之间传递变量。 例如：

存档ClassN1.dart N1类内容变量1 = 0

存档ClassN2.dart N2类计算sumVariables = Variable1 * 2;

几天来，我一直在寻找有关它的信息。 从已经非常感谢您！

    FirebaseApp.configure()

    // View Controller Setup
    window = UIWindow(frame: UIScreen.main.bounds)
    window?.makeKeyAndVisible()

    let mainViewController = ViewController()
    mainViewController.view.backgroundColor = .black
    window?.rootViewController = UINavigationController(rootViewController: mainViewController)

档案编号2.dart -状态= adecuado * 2

import 'package:flutter/material.dart';
import 'Funtion_Calculate.dart';

class DatesPrincipal extends StatelessWidget {
  get left => null;

  @override
  Widget build(BuildContext context) {
    return new Container(
      child: Row(
        children: <Widget>[
          new Container(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: <Widget>[ //First linea of dates
                NumberDates(),
                StatusNPS(),
                PutDatesNPS()
              ],
            ),
          )
        ],
      ),
    );
  }
}

class NumberDates extends StatefulWidget {
  @override
  _NumberDatesState createState() => _NumberDatesState();
}

class _NumberDatesState extends State<NumberDates> {

  var adecuado = '0';

  Widget build(BuildContext context) {
    Widget iconList;
      return iconList = DefaultTextStyle.merge(
      style: descTextStyle,
      child: Container(
        child: new Row(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            Container(
              child: Column(
                children: <Widget>[
                  Text(adecuado,
                    style: TextStyle(
                      fontSize: 18
                    ),
                  ),
                  Padding(
                    padding: EdgeInsets.all(4),
                  ),
                  Text('Adecuado')
                ],
              ),
              width: 100.0,
            ),
          ],
        ),
      )
    );
  }
}