set state in the on change

Question

import 'package:flutter/material.dart';

bool jov = false;

class boox extends StatelessWidget {
  const boox({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      drawer: Drawer(),
      body: Container(
        child: Column(children: [
          Row(
            children: [
              Text("jordn"),
              Checkbox(
                  value: jov,
                  onChanged: (String val) {
                    setstate(() {
                      jov = val;
                    });
                  })
            ],
          ),
          Row(
            children: [Text("data")],
          )
        ]),
      ),
    );
  }
}

The setstate cannot appear on onchanged and cant take it

I am difintion the variables and the problem still appear

and try to write the code and still appear this problem if any can fix him to me or no way

Answer 1

You need to use StatefulWidget to use setState and onChanged will provide nullable bool for Checkbox it will be onChanged: (bool? value) {

class boox extends StatefulWidget {
  const boox({super.key});

  @override
  State<boox> createState() => _booxState();
}

class _booxState extends State<boox> {
  bool jov = false;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      drawer: Drawer(),
      body: Container(
        child: Column(children: [
          Row(
            children: [
              Text("jordn"),
              Checkbox(
                value: jov,
                onChanged: (bool? value) {
                  setState(() {
                    jov = value??false;
                  });
                },
              )
            ],
          ),
          Row(
            children: [Text("data")],
          )
        ]),
      ),
    );
  }
}

More about StatefulWidget

Answer 2

Your example wouldn't work

boox is Stateless widget and doesn't have any setState method In your case you can see changes your app should update a tree node which belong boox widget

You have to use Stateful widget instead