Checkbox in Flutter

The Checkbox widget creates a checkbox input that the user can toggle between selected and unselected states.
 Here is a simple example showing how to use the checkbox widget:

There Are Some Common Attributes for FractionallySizedBox

Here's a simple example of using a Checkbox Flutter:

File open lib->main.dart file −

import 'package:flutter/material.dart';

void main() {
  runApp(
    MyApp()
  );
}
class MyApp extends StatefulWidget{

  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  bool _isChecked=false;
  @override
  Widget build(BuildContext context) {
    return   MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.blue,
          title: Text('TextField Example',
              style:TextStyle(fontSize: 20,color: Colors.white)),
        ),
        body:
        Container(
          alignment: Alignment.center,
          child: Column(
            children: [
              Checkbox(value: _isChecked,
                  onChanged: (bool? value){

                    setState(() {
                      _isChecked = value ?? false;
                    });
                  }
              ),
              Text("Check Box is $_isChecked")

            ],
          ),
        ),
      ),
    );
    
    
      

  }
}

Open Device Manager, run the emulator, and then run the application. Next, check the working output and check the output you declared in your code.

Output: