getter 'pokemon' 被调用为 null。接收者：空尝试调用：pokemon

Question

我正在尝试制作一个口袋妖怪应用程序。但我收到此错误：

“getter 'pokemon' 被调用为 null。

接收者：空

尝试调用：pokemon”

I am putting error page to here.

我使用这个 API url 来获取数据“https://raw.githubusercontent.com/Biuni/PokemonGO-Pokedex/master/pokedex.json”

我的口袋妖怪课程在这里：**

class Pokedex {
  List<Pokemon> pokemon;

  Pokedex({
      this.pokemon});

  Pokedex.fromJson(dynamic json) {
    if (json["pokemon"] != null) {
      pokemon = [];
      json["pokemon"].forEach((v) {
        pokemon.add(Pokemon.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    var map = <String, dynamic>{};
    if (pokemon != null) {
      map["pokemon"] = pokemon.map((v) => v.toJson()).toList();
    }
    return map;
  }

}

class Pokemon {
  int id;
  String num;
  String name;
  String img;
  List<String> type;
  String height;
  String weight;
  String candy;
  int candyCount;
  String egg;
  double spawnChance;
  int avgSpawns;
  String spawnTime;
  List<double> multipliers;
  List<String> weaknesses;
  List<Next_evolution> nextEvolution;

  Pokemon({
      this.id, 
      this.num, 
      this.name, 
      this.img, 
      this.type, 
      this.height, 
      this.weight, 
      this.candy, 
      this.candyCount, 
      this.egg, 
      this.spawnChance, 
      this.avgSpawns, 
      this.spawnTime, 
      this.multipliers, 
      this.weaknesses, 
      this.nextEvolution});

  Pokemon.fromJson(dynamic json) {
    id = json["id"];
    num = json["num"];
    name = json["name"];
    img = json["img"];
    type = json["type"] != null ? json["type"].cast<String>() : [];
    height = json["height"];
    weight = json["weight"];
    candy = json["candy"];
    candyCount = json["candy_count"];
    egg = json["egg"];
    spawnChance = json["spawn_chance"];
    avgSpawns = json["avg_spawns"];
    spawnTime = json["spawn_time"];
    multipliers = json["multipliers"] != null ? json["multipliers"].cast<double>() : [];
    weaknesses = json["weaknesses"] != null ? json["weaknesses"].cast<String>() : [];
    if (json["next_evolution"] != null) {
      nextEvolution = [];
      json["next_evolution"].forEach((v) {
        nextEvolution.add(Next_evolution.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    var map = <String, dynamic>{};
    map["id"] = id;
    map["num"] = num;
    map["name"] = name;
    map["img"] = img;
    map["type"] = type;
    map["height"] = height;
    map["weight"] = weight;
    map["candy"] = candy;
    map["candy_count"] = candyCount;
    map["egg"] = egg;
    map["spawn_chance"] = spawnChance;
    map["avg_spawns"] = avgSpawns;
    map["spawn_time"] = spawnTime;
    map["multipliers"] = multipliers;
    map["weaknesses"] = weaknesses;
    if (nextEvolution != null) {
      map["next_evolution"] = nextEvolution.map((v) => v.toJson()).toList();
    }
    return map;
  }

}

class Next_evolution {
  String num;
  String name;

  Next_evolution({
      this.num, 
      this.name});

  Next_evolution.fromJson(dynamic json) {
    num = json["num"];
    name = json["name"];
  }

  Map<String, dynamic> toJson() {
    var map = <String, dynamic>{};
    map["num"] = num;
    map["name"] = name;
    return map;
  }

}

<块引用>

这是我的 main.dart 文件：

import 'package:flutter/material.dart';
import 'package:pokemon_api/pokemon_list.dart';

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: PokemonList(),
    );
  }
}

<块引用>

这是我的 pokemon_list.dart 文件：

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

import 'model/pokedex.dart';

class PokemonList extends StatefulWidget {
  const PokemonList({Key key}) : super(key: key);

  @override
  _PokemonListState createState() => _PokemonListState();
}

class _PokemonListState extends State<PokemonList> {

  String url =
      "https://raw.githubusercontent.com/Biuni/PokemonGO-Pokedex/master/pokedex.json";
  Pokedex pokedex;
  var response;
  Future<Pokedex> PokemonlariGetir() async {
     response= await http.get(Uri.parse(url)).then((value){
      var decodedJson = json.decode(response.body);
      pokedex = Pokedex.fromJson(decodedJson);
    });

    debugPrint(pokedex.toString());
    return pokedex;
  }
  @override


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Pokemon"),
      ),
      body: FutureBuilder(
          future: PokemonlariGetir(),
          builder: (context, AsyncSnapshot<Pokedex> gelenPokedex) {
            if (gelenPokedex.connectionState == ConnectionState.waiting) {
              return Center(
                child: CircularProgressIndicator(),
              );
            } else if (gelenPokedex.connectionState==ConnectionState.done) {
              return GridView.builder(
                  gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                      crossAxisCount: 2),
                  itemBuilder: (context,index){
                    return Text(gelenPokedex.data.pokemon[index].name);
                  });
             // return  GridView.count(crossAxisCount: 2,children:gelenPokedex.data.pokemon.map((poke){
             //    return Text(poke.name);
             //  }).toList(),);
            }else{
              return Center(child: CircularProgressIndicator(),);
            }
          }),
    );
  }
}