Can anyone help me understand this piece of code:

 String? userName = "";   
 String? userEmail = ""; 
 AuthService authService = AuthService();

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

while defining gettingUserData(), using async, await needs hotreload to show the email

gettingUserData() async {     
setState(() async {       
userName = await HelperFunction.getUsername();       
userEmail = await HelperFunction.getUseremail();     
});   
} 

But defining it using .then doesn't need hot relaod

gettingUserData() {
    HelperFunction.getUseremail().then((value) {
      setState(() {
        userEmail = value;
      });
    });

    HelperFunction.getUsername().then((value) {
      setState(() {
        userName = value;
      });
    });
  }

Can anyone help me understand why this is?

CodePudding user response：

The two versions are not equivalent. The Future.then version calls setState after each Future completes.

The await version calls setState with an asynchronous callback, which setState does not expect. Since setState expects a VoidCallback argument, it expects its callback to complete synchronously, and it will not be awaited. setState therefore executes and returns immediately before waiting for either of the Futures complete.

One way to correct your await version is to await the Futures first and to then call setState:

Future<void> gettingUserData() async {     
  var userName = await HelperFunction.getUsername();
  var userEmail = await HelperFunction.getUseremail();
  setState(() {
    this.userName = userName;
    this.userEmail = userEmail;
  });
}