我已解决问题，请尝试运行以下代码。

说明

• 初始化布尔类型列表

  var userStatus = List（）;

• 在添加用户时将布尔值false添加到列表中，如下面的代码所示

  userStatus.add（false）

• 现在在复选框中设置一个值

  值：userStatus [index]

• 在复选框的onChanged事件中，使用设置状态切换用户状态

  userStatus [index] =！userStatus [index];

import 'package:flutter/material.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'dart:convert';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,title: 'Flutter Demo',theme: ThemeData(
        primarySwatch: Colors.blue,),home: Location(),);
  }
}


class Location extends StatefulWidget {
  @override
  _LocationState createState() => _LocationState();
}

class _LocationState extends State<Location> {
  //initState
  bool selected = false;
  var userStatus = List<bool>();

  Future<List<User>> _getUsers() async {
    var data = await http
        .get("http://www.json-generator.com/api/json/get/cdjVKlMEde?indent=2");

    var jsonData = json.decode(data.body);

    List<User> users = [];

    for (var u in jsonData) {
      User user =
      User(u["index"],u["about"],u["name"],u["email"],u["picture"]);

      users.add(user);
      userStatus.add(false);
    }

    print(users.length);

    return users;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Select City'),body: Container(
        child: FutureBuilder(
          future: _getUsers(),builder: (BuildContext context,AsyncSnapshot snapshot) {
            print(snapshot.data);
            if (snapshot.data == null) {
              return Container(child: Center(child: Text("Loading...")));
            } else {
              return ListView.builder(
                itemCount: snapshot.data.length,itemBuilder: (BuildContext context,int index) {
                  return ListTile(
                    leading: CircleAvatar(
                      backgroundImage:
                      NetworkImage(snapshot.data[index].picture),title: Text(snapshot.data[index].name),subtitle: Text(snapshot.data[index].email),trailing: Checkbox(
                        value: userStatus[index],onChanged: (bool val) {
                          setState(() {
                            userStatus[index] = !userStatus[index];
                          });
                        }),onTap: () {
                      Navigator.push(
                          context,new MaterialPageRoute(
                              builder: (context) =>
                                  DetailPage(snapshot.data[index])));
                    },);
                },);
            }
          },);
  }
}

class DetailPage extends StatelessWidget {
  final User user;

  DetailPage(this.user);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(user.name),));
  }
}

class User {
  final int index;
  final String about;
  final String name;
  final String email;
  final String picture;

  User(this.index,this.about,this.name,this.email,this.picture);
}