我正在从Firebase获得一个列表。列表加载如预期，但是我有两个问题。
1-当列表中一个项目中的按钮被禁用时，其他项目中的所有按钮也将被禁用。我不想发生这种事。我怎么能通过这个？
2-我得到了"；positiveCount"；以及"；否定计数"；来自防火基地RTDB。我想得到total(positiveCount+negativeCount(，然后计算"；positiveCount"；。(示例：positiveCount=2，negativeCount=2中，positiveCount的百分比应为50%(。问题是，如果只有一个项目被加载，它就可以完美地工作。如果加载了多个项目，则会出现错误。
例外：
Exception has occurred.
UnsupportedError (Unsupported operation: Infinity or NaN toInt)
我的代码：
import 'package:colour/colour.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:google_fonts/google_fonts.dart';
import 'dart:async';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
// import 'package:shared_preferences/shared_preferences.dart';
class VaccineCenterList extends StatefulWidget {
const VaccineCenterList({key}) : super(key: key);
static const String idScreen = "VaccineCenterList";
@override
_VaccineCenterListState createState() => _VaccineCenterListState();
}
class _VaccineCenterListState extends State<VaccineCenterList> {
final databaseReference = FirebaseDatabase.instance.reference();
final firestoreInstance = FirebaseFirestore.instance;
FirebaseAuth auth = FirebaseAuth.instance;
List<Hospitals> driverList = [];
late String isTrueOrFalse = "False";
// // double percentageInt = 0.0;
int totalVotes = 0;
// int percentage = 0;
int positiveCount = 0;
int negativeCount = 0;
bool buttonPressed = true;
TextEditingController hospitalCountyEditingController =
TextEditingController();
Future<List<Hospitals>> getHospitalDetails() async {
try {
if ((hospitalCountyEditingController.text != "") &&
(hospitalCountyEditingController.text != " ")) {
databaseReference
.child("Hospitals")
.child(hospitalCountyEditingController.text)
.onValue
.listen(
(event) {
setState(
() {
var value = event.snapshot.value;
driverList = Map.from(value)
.values
.map((e) => Hospitals.fromJson(Map.from(e)))
.toList();
},
);
},
);
} else {}
} catch (e) {
}
return driverList;
}
calculatePositivePercentage(
positiveCount, negativeCount) {
// this method gets the number of "yes" and "no" votes. Then calculates the
// percentage of people who voted "yes".
// total = positiveCount + negativeCount;
// percentage = (positiveCount * 100) ~/ total;
totalVotes = positiveCount + negativeCount;
int percentage = positiveCount * 100;
double votePercentage = percentage / totalVotes;
return votePercentage;
}
@override
void initState() {
super.initState();
print("I'm in the vaccine list search screen");
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.grey[100],
appBar: AppBar(
backgroundColor: Colors.grey[100],
centerTitle: true,
elevation: 0,
iconTheme: const IconThemeData(
color: Colors.black,
),
title: Text(
"Pamoja",
style: GoogleFonts.lexendMega(
fontWeight: FontWeight.bold,
color: Colors.black,
fontSize: 35,
),
),
),
body: GestureDetector(
onTap: () {
FocusScope.of(context).requestFocus(FocusNode());
},
child: SingleChildScrollView(
child: Column(
children: [
Container(
padding: const EdgeInsets.all(8.0),
child: TextField(
controller: hospitalCountyEditingController,
keyboardType: TextInputType.text,
textCapitalization: TextCapitalization.words,
decoration: InputDecoration(
border: const OutlineInputBorder(
borderSide: BorderSide(
color: Colors.black,
style: BorderStyle.solid,
width: 1,
),
),
labelText: "Search County",
labelStyle: const TextStyle(
fontSize: 14.0,
color: Colors.blueGrey,
),
hintStyle: GoogleFonts.lexendMega(
color: Colors.grey,
fontSize: 10,
),
),
style: GoogleFonts.lexendMega(
fontSize: 14,
color: Colors.black,
),
),
),
ElevatedButton(
onPressed: () {
buttonPressed = false;
setState(() {
FocusScope.of(context).requestFocus(
FocusNode(),
);
driverList.clear();
if (hospitalCountyEditingController.text == "" ||
hospitalCountyEditingController.text == " ") {
isTrueOrFalse = "False";
} else {
isTrueOrFalse = "True";
}
});
getHospitalDetails();
},
child: Text(
"Search",
style: GoogleFonts.lexendMega(
fontWeight: FontWeight.bold,
),
),
),
SizedBox(
height: MediaQuery.of(context).size.height,
// color: Colors.black,
child: Padding(
padding: const EdgeInsets.all(12.0),
child: driverList.isEmpty
? Center(
// child: CircularProgressIndicator(),
child: (isTrueOrFalse == "True")
? const CircularProgressIndicator()
: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
"Search for one of the counties below",
style: GoogleFonts.lexendMega()),
),
Text(
"Nairobi, Baringo, Busia, Bomet, Bungoma, Elgeyo Marakwet, Embu, Garissa, Homa Bay, Isiolo, Kajiado, Kakamega, Kericho, Kiambu, Kilifi, Kirinyaga, Kisii, Kisumu, Kitui, Kwale, Laikipia, Lamu, Machakos, Makueni, Mandera, Marsabit, Meru, Migori, Mombasa, Muranga, Nakuru, Nandi, Narok, Nyamira, Nyandarua, Nyeri, Samburu, Siaya County, Taita Taveta, Tana River County, Tharaka Nithi, Trans Nzoia, Turkana, Uasin Gishu, Vihiga, Wajir, West Pokot",
textAlign: TextAlign.center,
style: GoogleFonts.lexendMega(
fontWeight: FontWeight.bold,
),
),
],
),
)
: ListView.builder(
itemCount: driverList.length,
itemBuilder: (context, int index) {
final Hospitals hospitals = driverList[index];
final String hospitalLocaiton = hospitals.location;
final String hospitalPhone = hospitals.phone;
// final int totalVotes = hospitals.totalVotes;
final String hospitalName = hospitals.name;
// final String county = hospitals.county;
positiveCount = hospitals.positiveCount;
negativeCount = hospitals.negativeCount;
// final int percentage = positiveCount * 100;
// final double percentageInt =
// percentage / totalVotes;
// ignore: unused_local_variable
final double setpercentage =
calculatePositivePercentage(positiveCount, negativeCount);
**final percentageInt = setpercentage.toInt();**
return Padding(
padding: const EdgeInsets.all(8.0),
child: Card(
elevation: 0,
child: ExpansionTile(
title: Text(
hospitalName.toUpperCase(),
style: GoogleFonts.lexendMega(),
textAlign: TextAlign.center,
),
children: [
Column(
children: [
Container(
child: (hospitalPhone.isNotEmpty)
? ElevatedButton(
onPressed: () {
Clipboard.setData(
ClipboardData(
text: hospitalPhone,
),
);
ScaffoldMessenger.of(
context)
.showSnackBar(
const SnackBar(
backgroundColor:
Colors.green,
content: Text(
"Number Copied",
textAlign:
TextAlign.center,
),
),
);
},
child: Text(
hospitalPhone,
textAlign: TextAlign.center,
style:
GoogleFonts.lexendMega(
fontSize: 13),
),
style:
ElevatedButton.styleFrom(
elevation: 0,
),
)
: const Text(""),
),
const SizedBox(
height: 5,
),
hospitalLocaiton.isNotEmpty
? Container(
padding:
const EdgeInsets.all(8),
decoration: BoxDecoration(
border: Border.all(
color: Colors.black,
),
borderRadius:
BorderRadius.circular(10),
),
child: Text(
hospitalLocaiton,
textAlign: TextAlign.center,
style: GoogleFonts.lexendMega(
fontSize: 12,
),
),
)
: Text(
hospitalLocaiton,
textAlign: TextAlign.center,
style: GoogleFonts.lexendMega(
fontSize: 12,
),
),
const SizedBox(
height: 10,
),
Text(
"$percentageInt% (percent) of voters say this hospital administer vaccines.",
textAlign: TextAlign.center,
style: GoogleFonts.lexendMega(
fontWeight: FontWeight.bold,
fontSize: 12,
color: Colors.deepPurple[400],
),
),
const SizedBox(
height: 10,
),
const Divider(
// thickness: 1,
indent: 20,
endIndent: 20,
color: Colors.black87,
),
const SizedBox(
height: 10,
),
Text(
"Does this Hospital administer Vaccines?n(To help the public, please vote only if you know.)",
textAlign: TextAlign.center,
style: GoogleFonts.lexendMega(
fontSize: 12,
fontWeight: FontWeight.bold,
),
),
// Container(
// child: (positiveCount == 0)
// ? Text("Votes: $positiveCount")
// : Text("Votes: " +
// positiveCount.toString()),
// ),
Column(
children: [
Row(
mainAxisAlignment:
MainAxisAlignment.spaceEvenly,
children: [
ElevatedButton(
onLongPress: buttonPressed
? () {
buttonPressed = false;
ScaffoldMessenger.of(
context)
.showSnackBar(
const SnackBar(
backgroundColor:
Colors
.purpleAccent,
content: Text(
"Vote Removed",
textAlign:
TextAlign
.center,
),
),
);
undoPositiveIncrement(
hospitalName);
}
: null,
onPressed: buttonPressed ? () {
ScaffoldMessenger.of(
context)
.showSnackBar(
const SnackBar(
backgroundColor:
Colors.greenAccent,
content: Text(
"Voted Yes",
textAlign:
TextAlign.center,
),
),
);
positiveIncrement(
hospitalName);
} : null,
child: Text(
"Yes - $positiveCount",
style: GoogleFonts
.lexendMega(),
),
style:
ElevatedButton.styleFrom(
primary: Colour("#87D68D"),
),
),
ElevatedButton(
onLongPress: buttonPressed ? () {
ScaffoldMessenger.of(
context)
.showSnackBar(
const SnackBar(
backgroundColor:
Colors.purpleAccent,
content: Text(
"Vote Removed",
textAlign:
TextAlign.center,
),
),
);
undoNegativeIncrement(
hospitalName);
} : null,
onPressed: buttonPressed ? () {
ScaffoldMessenger.of(
context)
.showSnackBar(
const SnackBar(
backgroundColor:
Colors.redAccent,
content: Text(
"Voted",
textAlign:
TextAlign.center,
),
),
);
negativeIncrement(
hospitalName);
} : null,
child: Text(
"No - $negativeCount",
style: GoogleFonts
.lexendMega(),
),
style:
ElevatedButton.styleFrom(
primary: Colour("#E3655B"),
),
),
],
),
const SizedBox(
height: 10,
),
Text(
"Total No. of Votes: ",
style: GoogleFonts.lexendMega(
fontSize: 12),
),
const SizedBox(
height: 10,
),
Text(
"1 - To vote, tap oncen2 - To Undo vote, tap and hold",
style: GoogleFonts.lexendMega(
fontSize: 12,
),
textAlign: TextAlign.start,
),
const SizedBox(
height: 10,
),
],
),
],
),
],
),
),
);
},
),
),
),
],
),
),
),
);
}
}
class Hospitals {
final String name;
final String phone;
final String location;
// final String county;
final int positiveCount;
final int negativeCount;
// final int intPercentage;
// final int totalVotes;
Hospitals({
required this.name,
required this.phone,
required this.location,
// required this.county,
required this.positiveCount,
required this.negativeCount,
// required this.intPercentage,
// required this.totalVotes,
});
static Hospitals fromJson(Map<String, dynamic> json) {
return Hospitals(
name: json['HospitalName'],
phone: json['HospitalPhone'],
// county: json['county'],
location: json['HospitalAddres'],
positiveCount: json['poitiveCount'],
negativeCount: json['negativeCount'],
// intPercentage: json['intPercentage'],
// totalVotes: json['totalVotes']
);
}
}
问题2的解决方案：
calculatePositivePercentage(positiveCount, negativeCount) {
// this method gets the number of "yes" and "no" votes. Then calculates the
// percentage of people who voted "yes".
double votePercentage = 0;
if (positiveCount == 0 && negativeCount == 0) {
try {
return votePercentage.toInt();
} catch (e) {
print(e);
}
} else {
try {
totalVotes = positiveCount + negativeCount;
int percentage = positiveCount * 100;
votePercentage = percentage / totalVotes;
return votePercentage.toInt();
} catch (e) {
print(e);
}
}
}
防止禁用所有按钮而不是
bool buttonPressed = true;
使用
List<bool> buttonPressed = [true];
你的第二个错误是因为你可能没有从响应中获得int值。尝试
int.parse();
解析String到int