Flutter setState로 재랜더링하기

1. StatelessWidget -> StatefulWidget으로 바꾸기

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State {

  var a = 1;  //여기 만드는 변수는 state가 됩니다 
  @override
  Widget build(BuildContext context) {
    return Scaffold(생략);
  }
}  

2. setState() 사용

MaterialApp(
  home: Scaffold(
    floatingActionButtion: FloatingActionButton(
      child : Text(a.toString()),
      onPressed: (){ 
        setState((){
          a++
        });
      }
    ),
    appBar: AppBar(),
    body: 생략
  ),
)