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

Posted 2023-02-22

【中文标题】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

【英文标题】：Sum all numbers in a list or alternative way of adding a changing list of variables flutter

【发布时间】：2020-12-23 04:36:04

【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。

【参考方案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),
      ),
    );
  

【讨论】：

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