import 'package:flutter/material.dart';
import 'API.dart';

class BusInfomationScreen extends StatelessWidget { 
  final originToDestination; 
  final tableColor; 
  final nodeId;
  var busInfo;
  var busInfoList;

  BusInfomationScreen({ 
    this.originToDestination,
    this.tableColor,
    this.nodeId,
    this.busInfoList,
  }) {
    GetAPI getAPI = GetAPI(nodeID: nodeId); 
    busInfo = getAPI.fetchPost();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body:
      Container(
        color: Colors.blueGrey,
        child:
            FutureBuilder<Map<String, dynamic>>(
              future: busInfo, //fetchpost() == busInfoList
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  //return Text("${snapshot.data.values.toList()[0]["body"]["items"]["item"]}");
                  busInfoList = snapshot.data.values.toList()[0]["body"]["items"]["item"];
                  ///
                  debugPrint("${busInfoList[0]["arrtime"].runtimeType}"); // int
                  debugPrint("${busInfoList[0].runtimeType}"); // _InternalLinkedHashMap<String, dynamic>
                  debugPrint("${busInfoList}");
                  debugPrint("${busInfoList.runtimeType}"); // List<dynamic>

                  busInfoList.sort((a, b) => a["arrtime"].compareTo(b["arrtime"]));

busInfoList =

[{arrprevstationcnt: 7, arrtime: 499, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000012, routeno: 8, routetp: 간선버스, vehicletp: 일반차량}, {arrprevstationcnt: 14, arrtime: 1582, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000020, routeno: 16, routetp: 간선버스, vehicletp: 일반차량}, {arrprevstationcnt: 17, arrtime: 1503, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000169, routeno: 780, routetp: 좌석버스, vehicletp: 일반차량}, {arrprevstationcnt: 7, arrtime: 1200, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000193, routeno: 909, routetp: 간선버스, vehicletp: 일반차량}, {arrprevstationcnt: 2, arrtime: 142, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000206, routeno: 91(순환), routetp: 지선버스, vehicletp: 일반차량}, {arrprevstationcnt: 9, arrtime: 726, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000225, routeno: 780-1, routetp: 좌석버스,

例如)

busInfoList[0] = 

{arrprevstationcnt: 7, arrtime: 475, nodeid: ICB164000395, nodenm: 인천대입구역, routeid: ICB165000012, routeno: 8, routetp: 간선버스, vehicletp: 일반차량}

busInfoList[0]["arrtime"] =

386

像上面这样的代码，

busInfoList[index] 表示每条公交车的信息。 busInfoList[index]["arrtime"] 如您所见，表示到达时间为 int 类型。

因为我想按 arrtime 对 busInfoList 进行排序， 我用过这个

busInfoList.sort((a, b) => a["arrtime"].compareTo(b["arrtime"]));

但是出现这个错误。

I/flutter (13902): Another exception was thrown: type '(dynamic, dynamic) => dynamic' is not a subtype of type '(dynamic, dynamic) => int' of 'compare'

我已经检查过 busInfoList[i]["arrtime"] 是 int 类型。 但是为什么会出现这个错误呢？

最佳答案

要了解问题，请运行此 Dart 代码:

var arr;
arr = [1, 23, 10, 17, 2];
arr.sort((a, b) => a.compareTo(b));

代码抛出异常:

Exception has occurred. _TypeError (type '(dynamic, dynamic) => dynamic' is not a subtype of type '(int, int) => int' of 'compare')

但是这段代码工作正常:

  (arr as List<int>).sort((a, b) => a.compareTo(b));

结论:您需要向编译器提示您的数据类型。

关于Flutter，尝试对列表进行排序时发生类型错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57025064/