Can I use setState() inside a function that is called from a StateFull?

Question

I have this code:

class buildApp extends StatefulWidget {
  const buildApp({super.key});
  @override
  State<buildApp> createState() => _buildAppState();
}
class _buildAppState extends State<buildApp> {
  @override
  Widget build(BuildContext context) {
    return  LayoutBuilder(builder: (context,constraints){
       if(constraints.maxWidth <= 768){
         return buildPortrait(State);
       }
       return const Text('');
    });
  }
}

buildPortrait(){
   ...
}

The problem is that inside the buildPortrait() I need to call setState because I have a DropDownButton and a onChanged event but steState doesn't exist there. Is possible to do it? Maybe get the state and pass as variable?

Off course that I am open for news approaches...I am trying to create a portrait and lasdscape responsive app.

Thank you.

I can create all the two functions build Portrait() and build LandScape() inside the class buildApp but the code will get a mess.

Answer 1

as I mentioned on the comment

1. setState only avaliable inside the State class. in your case, you named it as _buildAppState

class _buildAppState extends State<buildApp> {
  @override
  Widget build(BuildContext context) {
  // widget code will be here 
  }

//put your function inside , so you can free to use it
 buildPortrait(){
   ...
 }

} // close bracket for _buildAppState class

---

2. in other case, some developer wants to separate their method to another file. this code style help developer to avoid to much line code in a file.

if you want to separate your method, you may use this workaround:

your method in another file,

• helper.dart

buildPortrait({VoidCallback? sst}){

   // your code here
   
   // every time you want to call setState, just invoke the sst
   sst?.call(); // this will execute setState in the parent class
   ...
}

• buildApp.dart

class buildApp extends StatefulWidget {
  const buildApp({super.key});
  @override
  State<buildApp> createState() => _buildAppState();
}
class _buildAppState extends State<buildApp> {
  @override
  Widget build(BuildContext context) {
  return Column(
      children:[
         ElevatedButton(
            onPressed: () {
              /// now you can use it and pass the params setState
              buildPortrait(sst: () => setState(() {}));
            },
            child: Text("nasdasda")
          )
}