error: The function can't be unconditionally invoked because it can be 'null'. with flutter

Question

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:ourchat/screens/home/chat_screen.dart';
import 'package:ourchat/screens/welcome/welcome_screen.dart';

class LandingPage extends StatefulWidget{
  @override
  State<LandingPage> createState() => _LandingPageState();
}

class _LandingPageState extends State<LandingPage>{

  late User _user;

  @override
  void initState(){
    // TODO: implement initState
    super.initState();
    _checkUser();
  }

  @override
  Widget build(BuildContext context) {
    if(_user == null){
      return WelcomeScreen();
    }else{
      return HomePage();
    }
  }

  Future<void> _checkUser() async{
    _user = await FirebaseAuth.instance.currentUser(); //=> ERROR

  }
}

我应该在这里做什么？当我放一个感叹号时，我也得到了一个错误，不明白为什么。我指定了我从哪里得到 error.Thanks 来寻求你的帮助

Answer 1

试试不带 () 的 FirebaseAuth.instance.currentUser，因为这不是函数。

Answer 2

使用用户？ _用户;而不是迟到的用户_user；在第 6 行

error: The function can't be unconditionally invoked because it can be 'null'. with flutter

error: The function can't be unconditionally invoked because it can be 'null'. with flutter

flutter

flutter-layout