我想制作一个奖励积分应用程序，因为我使用了随机函数.
I want to make a reward points app, for that i use a random function.
问题是我不知道如何将此号码添加到先前的号码.得到总分.
The problem is i don't know how to add this number to the previous number. to get sum points.
这是我想要在此处求和的结果.
修改后，我收到此错误
这是我的奖励应用程序的完整代码
here is the complete code for my reward app
rewards.dart
import 'dart:async'; import 'package:fid786/Services/CardScreen.dart'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; import 'package:fid786/styles.dart'; import 'package:fid786/Services/ClasNumber.dart'; class RewardsScreen extends StatefulWidget { @override _RewardsScreenState createState() => _RewardsScreenState(); } class _RewardsScreenState extends State<RewardsScreen> { @override void initState() { super.initState(); startTimer(); } startTimer() async{ var duration=Duration(seconds: 4); return Timer(duration,route); } route(){ Navigator.pushReplacement(context, MaterialPageRoute(builder: (context)=>CardScreen())); } @override Widget build(BuildContext context) { return Scaffold( resizeToAvoidBottomPadding: false, body: AnnotatedRegion<SystemUiOverlayStyle>( value: SystemUiOverlayStyle.light, child: Container( height: MediaQuery.of(context).size.height, width: MediaQuery.of(context).size.width, decoration: BoxDecoration( gradient: LinearGradient( begin: Alignment.topCenter, end: Alignment.bottomCenter, stops: [0.1, 0.4, 0.7, 0.9], colors: [ Color(0xFF3594DD), Color(0xFF4563DB), Color(0xFF5036D5), Color(0xFF5B16D0), ], ), ), child: Padding( padding: EdgeInsets.only(top:80), child: Column( crossAxisAlignment: CrossAxisAlignment.stretch, children: <Widget>[ Expanded( flex: 8, child:Container( height: MediaQuery.of(context).size.height, width: MediaQuery.of(context).size.width, //height: 600.0, child: PageView( children: <Widget>[ Padding( padding: EdgeInsets.symmetric(horizontal: 2), child: Column( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ Center( child: ClipRRect( borderRadius: BorderRadius.circular(50.0), child: Image( image: AssetImage( 'assets/images/congrats.gif', ), height: 300.0, width: 300.0, fit: BoxFit.fill, ), ), ), SizedBox(height: 30.0), Text( ' Congratulations, You have Got', style: kTitleStyle, ), SizedBox(height: 20.0), Center( child:Text( ClassName.generateRandomNumber().toString(), style: TextStyle(color: Colors.greenAccent, fontWeight: FontWeight.bold, fontSize: 50)), ), SizedBox(height: 10.0), Center( child:Text( ' Points ', style: kTitleStyle, ), ), SizedBox(height: 50.0), Center( child:Text( 'Earn More Points and Win Prizes ', style: TextStyle( color: Colors.yellowAccent, fontWeight: FontWeight.bold, fontSize: 16, fontFamily: 'muso', decoration: TextDecoration.underline), ), ), ], ), ), ], ), ), ), ], ), ), ), ), ); } }文件CardScreen.dart
import 'package:flutter/material.dart'; import 'package:firebase_auth/firebase_auth.dart'; import 'package:cloud_firestore/cloud_firestore.dart'; import 'package:font_awesome_flutter/font_awesome_flutter.dart'; import 'package:fid786/ScanQR/Card_Scanner.dart'; import 'package:fid786/Authentification/LogInScreen.dart'; import 'package:fid786/Services/ClasNumber.dart'; class CardScreen extends StatefulWidget { @override _CardScreenState createState()=>_CardScreenState(); } class _CardScreenState extends State<CardScreen>{ FirebaseAuth auth=FirebaseAuth.instance; Future<void>logOut() async{ FirebaseUser user=auth.signOut() as FirebaseUser; return user; } @override void initState() { super.initState(); } int points = 0; int generateNumber() { int newPoints = ClassName.generateRandomNumber(); setState(() { points += newPoints; }); return points; } @override Widget build(BuildContext context){ return Scaffold( backgroundColor:Color(0xffffffff), appBar:AppBar( backgroundColor: Colors.greenAccent, title:Text("Loyalty Points"), actions: <Widget>[ SizedBox(width:1.0), FlatButton.icon(onPressed: (){ logOut(); Navigator.pushReplacement(context, MaterialPageRoute(builder: (BuildContext context)=>LogInScreen())); }, icon: Icon(Icons.shopping_cart,size: 40.0,color: Colors.pinkAccent,), label: Text("Log Out",style: TextStyle(color: Colors.pinkAccent),)) ], ), body: StreamBuilder( stream:Firestore.instance.collection('screen').snapshots(), builder:(context,snapshot){ if(!snapshot.hasData) return Text(''); return Column( children: <Widget>[ Padding( padding: EdgeInsets.only(left: 8.0, right: 8.0,top: 40.0), child: Container( width: MediaQuery.of(context).size.width, height: 80.0, child: Padding( padding: EdgeInsets.only(top: 8.0, bottom: 8.0), child: Material( shape: Border.all(width: 2.0, color: Colors.blueAccent), color: Colors.white, elevation: 18.0, shadowColor: Color(0x802196F3), child: Center( child: Padding( padding: EdgeInsets.all(5.0), child: Row( // mainAxisAlignment: // MainAxisAlignment.spaceBetween, children: <Widget>[ Text( snapshot.data.documents[0]['player'], style: TextStyle( color: Colors.greenAccent, fontWeight: FontWeight.bold, fontSize: 18.0), ), // mainAxisAlignment: // MainAxisAlignment.spaceBetween, SizedBox(width:175), Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Text( generateNumber().toString(), style: TextStyle(color: Colors.greenAccent, fontWeight: FontWeight.bold, fontSize: 25)), Text( 'Points', style: TextStyle( color: Colors.pinkAccent, fontWeight: FontWeight.bold, fontSize: 16.0, fontFamily: 'muso'), ), ], ) ], ), ), ), ), ), ), ), ], ); } ), floatingActionButton: FloatingActionButton( backgroundColor: Color(0xFFFA7397), child: Icon( FontAwesomeIcons.listUl, color: Color(0xFFFDDE42), ), onPressed: () { Navigator.push( context, MaterialPageRoute( builder: (context) => HomePage(), fullscreenDialog: true), ); }, ) ); } }文件ClasNumber.dart
import 'dart:math'; class ClassName{ static int generateRandomNumber() { List<int> pointValue = [5,6,7,8,10,15]; return pointValue[new Random().nextInt(pointValue.length)]; } }推荐答案
您可以使用setState()函数来实现.
you can use setState() function to achieve this.
int points = 0; int newPoints = generateRandomNumber(); setState(() { points += newPoints });如果您想在全球范围内存储总积分值，则应查看共享的首选项包.
If you would like to store the total points value globally, you should look into the shared preferences package.
能够全局使用该函数的最佳方法是将其包装在单独的全局类中.
The best way to be able to use the function globally is to wrap it in a separate global class.
class ClassName{ static int generateRandomNumber() { return pointValue[new Random().nextInt(pointValue.length)]; } }然后在您的其他课程中，您可以这样调用:
And then in your other classes you could call like this:
ClassName.generateRandomNumber();您得到的错误是由于在build()函数外部调用setState所致.像这样将生成编号函数移到构建函数中
The error you got was due to calling setState outside of the build() function. Move the generate number function inside the build function like this
@override Widget build(BuildContext context){ int generateNumber() { int newPoints = ClassName.generateRandomNumber(); setState(() { points += newPoints; }); return points; }