FlutterFutureBuilder回傳null

在這里，我試圖將animedetailjson內部Future<void> getJsonanimedetail()回傳，Container以便我可以在（也許）一個小部件上顯示資料，但問題是，即使內部正常作業，它FutureBuilder也會回傳。我已經閱讀了一些關于這個問題的類似主題，但是我很難理解其他人的代碼，我對編程真的很陌生，所以我很抱歉提出同樣的問題（但使用我自己的代碼??）nullprintFuture<void> getJsonanimedetail()

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

class detailscreen extends StatefulWidget {
  detailscreen({Key? key}) : super(key: key);
  @override
  State<detailscreen> createState() => _detailscreenState();
}

class _detailscreenState extends State<detailscreen> {
  _detailscreenState();
  @override
  Future<void> getJsonanimedetail() async {
    final animedetailresponse = await http.get(
      Uri.parse('https://api.jikan.moe/v4/anime/5114/full'),   
        headers: {"Accept": "application/json"});
    if (animedetailresponse.statusCode == 200) {
      print('Anime Details FOUND');
    } else
      (print('Anime Details ERROR'));
    if (mounted) {
      setState(
        () {
          var animedetailjson = jsonDecode(animedetailresponse.body)['data'];
          print(animedetailjson['title']);
        },
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: FutureBuilder(
          future: getJsonanimedetail(),
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              print(snapshot.data);
              return CircularProgressIndicator();
            }
            return Center(child: Text(snapshot.data.toString()));
          },
        ),
      ),
    );
  }
}

順便說一句，這是我的第一個訓練營專案，但不幸的是，我選擇了錯誤的訓練營，他們太不專業了，聊天中的很多問題都沒有得到任何答復，即使問題很清楚，培訓師也經常跳到下一條訊息就在他回復的訊息上面，他竟然睡著了，雖然之前他說要開始在線直播??

uj5u.com熱心網友回復：

您需要遵循 FutureBuilder 結構，您可以查看評論鏈接。您當前的未來方法不回傳任何內容（void），這就是您得到 null 的原因

import 'dart:developer';

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

class detailscreen extends StatefulWidget {
  detailscreen({Key? key}) : super(key: key);
  @override
  State<detailscreen> createState() => _detailscreenState();
}

class _detailscreenState extends State<detailscreen> {
  Future<Map<String, dynamic>?> getJsonanimedetail() async {
    final animedetailresponse = await http.get(
        Uri.parse('https://api.jikan.moe/v4/anime/5114/full'),
        headers: {"Accept": "application/json"});

    if (animedetailresponse.statusCode == 200) {
      log('Anime Details FOUND');
      var animedetail =
          jsonDecode(animedetailresponse.body)['data'] as Map<String, dynamic>;
      return animedetail; // better return list
    } else {
      log('Anime Details ERROR');
    }
  }

  late final future = getJsonanimedetail();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: FutureBuilder(
          future: future,
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              return Text("empty Data");
            }

            if (snapshot.hasData) {
              return Center(child: Text("${snapshot.data?["title"]}"));
            }
            if (snapshot.hasError) {
              return Text("got Error");
            }

            return CircularProgressIndicator();
          },
        ),
      ),
    );
  }
}

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