将列表中的所有数字相加或添加变化的变量列表的替代方式颤动

Question

您好，我正在尝试构建一个资金管理应用程序。 我在添加列表中的所有数字时遇到问题。

我的想法是我有 2 个按钮（绿色和红色）。用户会添加一个数字，然后点击绿色或红色来显示他们收到的钱或花费的钱。

我无法获取列表的总数或对列表执行数学运算。

我可以使用任何替代方法吗？

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

class HomeScreen extends StatefulWidget {
  static final String routeName = "/home";
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {

  final myController = TextEditingController();
  List<String> in_out = ["One","Two","Three","Four"];
  List<int> amount = [1, 2, 3 ,4];
//  int sum = amount.reduce((a, b) => a + b);
  var money = 0;
  var newMoney = 0;
  var cash = 0;
  var income = 0;
  var spent = 0;


  @override
  Widget build(BuildContext context) {

    return Scaffold(
      resizeToAvoidBottomPadding: false,
      appBar: buildAppBar(),
      body: buildBody(),
    );
  }


  Widget buildAppBar(){
    return AppBar(
      title: Text('Money Managment App'),
    );
  }

  Widget buildTotal(){
   return Text('$newMoney');// res is 15
  }

  Widget buildBody(){
    return Container(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              GestureDetector(
                child: Icon(Icons.chevron_left,
                color: Colors.red,
                size: 40,),
                onTap: (){
                  addExpense();
                },
              ),

        Container(
          width: 150,
          child: TextField(
            controller: myController,
            keyboardType: TextInputType.number,
            autocorrect: true,
          ),
        ),

              GestureDetector(
                child: Icon(Icons.chevron_right,
                color: Colors.green,
                size: 40,),
                onTap: () {
                  addIncome();
                },
              ),
            ],
          ),

          buildTotal(),

          SizedBox(height: 20,),

          Container(
            height: 350,
            child: ListView.builder
              (
                itemCount: in_out.length,
                itemBuilder: (BuildContext ctxt, int index) {
                  return Container(
                    height: 30,
                    margin: EdgeInsets.all(2),
                    color: Colors.white,
                    child: Center(
                        child: Text('${in_out[index]} (${amount[index]})',
                          style: TextStyle(fontSize: 18),
                        )
                    ),
                  );
                }
            )
          ),
        ],
      ),
    );
  }

  void total(){
      income = cash + int.parse(myController.text);
      newMoney = money + income;
  }


  void addIncome(){
    setState(() {
      in_out.add('Income',);
      amount.add(int.parse(myController.text));
      total();
    });
  }

  void addExpense(){
    setState(() {
      in_out.add('Expense');
      amount.add(int.parse(myController.text));
    });
  }

  
}

我是 Flutter 的新手。

非常感谢任何关于学习的提示或视频推荐。 提前谢谢你。

Answer 1

您可以在下面复制粘贴运行完整代码
第一步：您可以使用class Money和List<Money>来记录历史
第 2 步：您可以将 Income 和 Expense 字符串传递给 total 函数，然后进行计算

代码sn-p

class Money {
  String in_out;
  int amount;

  Money({this.in_out, this.amount});
}

void total(String in_out) {
    //income = cash + int.parse(myController.text);
    if (in_out == 'Income') {
      newMoney = newMoney + int.parse(myController.text);
    } else {
      newMoney = newMoney - int.parse(myController.text);
    }
  }

  void addIncome() {
    setState(() {
      moneyList
          .add(Money(in_out: 'Income', amount: int.parse(myController.text)));
      /* in_out.add('Income',);
      amount.add(int.parse(myController.text));*/
      total('Income');
    });
  }

  void addExpense() {
    setState(() {
      moneyList
          .add(Money(in_out: 'Expense', amount: int.parse(myController.text)));
      /*in_out.add('Expense');
      amount.add(int.parse(myController.text));*/
      total('Expense');
    });
  }

工作演示

完整代码

import 'package:flutter/material.dart';

class Money {
  String in_out;
  int amount;

  Money({this.in_out, this.amount});
}

class HomeScreen extends StatefulWidget {
  static final String routeName = "/home";
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  final myController = TextEditingController();
  List<Money> moneyList = [];
  // List<String> in_out = ["One","Two","Three","Four"];
  //List<int> amount = [1, 2, 3 ,4];
//  int sum = amount.reduce((a, b) => a + b);
  var money = 0;
  var newMoney = 0;
  var cash = 0;
  var income = 0;
  var spent = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomPadding: false,
      appBar: buildAppBar(),
      body: buildBody(),
    );
  }

  Widget buildAppBar() {
    return AppBar(
      title: Text('Money Managment App'),
    );
  }

  Widget buildTotal() {
    return Text('$newMoney'); // res is 15
  }

  Widget buildBody() {
    return Container(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              GestureDetector(
                child: Icon(
                  Icons.chevron_left,
                  color: Colors.red,
                  size: 40,
                ),
                onTap: () {
                  addExpense();
                },
              ),
              Container(
                width: 150,
                child: TextField(
                  controller: myController,
                  keyboardType: TextInputType.number,
                  autocorrect: true,
                ),
              ),
              GestureDetector(
                child: Icon(
                  Icons.chevron_right,
                  color: Colors.green,
                  size: 40,
                ),
                onTap: () {
                  addIncome();
                },
              ),
            ],
          ),
          buildTotal(),
          SizedBox(
            height: 20,
          ),
          Container(
              height: 350,
              child: ListView.builder(
                  itemCount: moneyList.length,
                  itemBuilder: (BuildContext ctxt, int index) {
                    return Container(
                      height: 30,
                      margin: EdgeInsets.all(2),
                      color: Colors.white,
                      child: Center(
                          child: Text(
                        '${moneyList[index].in_out} (${moneyList[index].amount})',
                        style: TextStyle(fontSize: 18),
                      )),
                    );
                  })),
        ],
      ),
    );
  }

  void total(String in_out) {
    //income = cash + int.parse(myController.text);
    if (in_out == 'Income') {
      newMoney = newMoney + int.parse(myController.text);
    } else {
      newMoney = newMoney - int.parse(myController.text);
    }
  }

  void addIncome() {
    setState(() {
      moneyList
          .add(Money(in_out: 'Income', amount: int.parse(myController.text)));
      /* in_out.add('Income',);
      amount.add(int.parse(myController.text));*/
      total('Income');
    });
  }

  void addExpense() {
    setState(() {
      moneyList
          .add(Money(in_out: 'Expense', amount: int.parse(myController.text)));
      /*in_out.add('Expense');
      amount.add(int.parse(myController.text));*/
      total('Expense');
    });
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: HomeScreen(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}