将所有数字以列表形式求和或以添加变量变动列表的替代方式求和

问题描述

您好，我正在尝试构建一个资金管理应用程序。 我在将所有数字添加到列表中时遇到问题。

我的想法是我有2个按钮（绿色和红色）。用户可以添加一个数字，然后点击绿色或红色以显示收到的钱或已花费的钱。

我无法获得列表总数，也无法对列表进行数学运算。

我可以使用其他替代方法吗？

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,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));
    });
  }

  
}

我是新来的人。

任何有关学习的技巧或视频建议将不胜感激。 预先谢谢你。

解决方法

您可以在下面复制粘贴运行完整代码
步骤1：您可以使用class Money和List<Money>来记录历史记录
步骤2：您可以将Income和Expense字符串传递给total函数，然后计算

代码段

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,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('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),);
  }
}