ListView.builder在操作之前不顯示任何內容

我創建了一個類，它接收 firebase firestore 中資料的 ID，并使用 Listview.builder 顯示內容。我確認該類正確地從上一個類中獲取資料，并且我看不到任何錯誤訊息，但結果什么也沒顯示。

class list_topic extends StatefulWidget{
  const list_topic({Key? key, required this.topic_send}) : super(key: key);
  final List<dynamic> topic_send ;
  @override
  _list_topicState createState() => _list_topicState();
}

class _list_topicState extends State<list_topic> {
  void initState() {
    super.initState();
    getData();
  }
  List<dynamic> topicAll = [];
  List<String> topicTitle = [];
  List<String> topicId = [];
  List<String> topicAbstract = [];
  List<String> topicWriter = [];
  List<int> topicVoteLeft = [];
  List<int> topicVoteRight = [];

  Future<void> getData() async {
    List<dynamic> topicReceived = widget.topic_send;
    for (int i = 0; i < topicReceived.length; i  ) {
      FirebaseFirestore.instance
          .collection('topic')
          .doc(topicReceived[i].toString())
          .get()
          .then((DocumentSnapshot doc) {
        final data_ = doc.data() as Map<String, dynamic>;
       // Future.delayed(Duration(milliseconds : 0),(){
          String abs = data_['abstract'];
          String title = data_['title'];
          String writer = data_['writer'];
          int vl = data_['vote_left'];
          int vr = data_['vote_right'];
          topicId.add(topicReceived[i]);
          topicTitle.add(title);
          topicAbstract.add(abs);
          topicWriter.add(writer);
          topicVoteLeft.add(vl);
          topicVoteRight.add(vr);
          topicAll.add(topicTitle);
          topicAll.add(topicAbstract);
          topicAll.add(topicWriter);
          topicAll.add(topicVoteLeft);
          topicAll.add(topicVoteRight);
          print('313131313131');
          print(topicId.length);
          print(topicTitle.length);
          print(topicAbstract.length);
          print('24242424242424');

      //  });
      });
    }
    //return topicAll;
  }
  @override
  Widget build(BuildContext context) {
   // getData();

    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.white,
        toolbarHeight: 1.0,
      ),

      body:
      Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          Align(
            alignment: Alignment.topLeft,
            child:SizedBox(
              height:30,
              width:20,
              child:
              TextButton(onPressed: (){

                Navigator.of(context).pop();

              },
                  style: TextButton.styleFrom( primary: Colors.brown,),
                  child: Icon(Icons.arrow_back)
              ),
            ),
          ),
          Padding(padding: EdgeInsets.symmetric(vertical: 10)),

          TextField(
            //focusNode: _focus,
            keyboardType: TextInputType.text,
            onChanged: (text){
              //  _streamSearch.add(text);
            },
            decoration: InputDecoration(
              //hintText: lang(0),
                border: InputBorder.none,
                icon: Padding(
                    padding: EdgeInsets.only(left: 13),
                    child: Icon(Icons.search))),
          ),

          SizedBox(
            height:MediaQuery.of(context).size.height*0.77,
            width:MediaQuery.of(context).size.width*0.8,

            child: ListView.builder(
              shrinkWrap: true,
              physics: BouncingScrollPhysics(),
              scrollDirection: Axis.vertical,
              itemCount: topicTitle.length,
              itemBuilder: (context,index){
                return GestureDetector(
                    onTap: (){
                      navi_to_debates(context,topicId[index]);
                      },
                    child:customCardCategory_topic(context, topicTitle[index], topicAbstract[index], Icons.topic_outlined, '22.PNG',topicVoteLeft[index],topicVoteRight[index])
                )
                ;
              },
            ),
          )
        ],
      ),
    );



  }
}

結果螢屏如下所示：

但是，如果我單擊 Textfield 進行搜索，Listview 會突然起作用。

由于我很陌生，我什至無法理解為什么會發生這種情況以及為什么沒有出現錯誤訊息。誰能告訴我我做錯了什么？

uj5u.com熱心網友回復：

您需要呼叫 setState 來更新 UI。你可以做

  @override
  void initState() {
    super.initState();
    getData().then((value) => setState((){}));
  }

或者

  Future<void> getData() async {
    ....
    setState(() {});
  }

并使用

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: true,
      appBar: AppBar(
        backgroundColor: Colors.white,
        toolbarHeight: 1.0,
      ),
      body: SingleChildScrollView(
        child: Column(

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