Form with Checkbox sample

main.dart

import 'package:flutter/material.dart';

void main() => runApp(const FormExampleApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(useMaterial3: true),
      home: Scaffold(
        appBar: AppBar(title: const Text('Form Sample')),
        body: const FormExample(),
      ),
    );
  }
}

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

  @override
  State<FormExample> createState() => _FormExampleState();
}

class _FormExampleState extends State<FormExample> {
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  bool isChecked = false;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16.0),
      child: Form(
        key: _formKey,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            TextFormField(
              decoration: const InputDecoration(
                filled: true,
                hintText: 'Enter your email',
              ),
              validator: (String? value) {
                if (value == null || value.isEmpty) {
                  return 'Please enter some text';
                }
                return null;
              },
            ),
            Checkbox(
              value: isChecked,
              onChanged: (bool? value) {
                setState(() {
                  isChecked = value!;
                });
              },
            ),
            Padding(
              padding: const EdgeInsets.symmetric(vertical: 16.0),
              child: ElevatedButton(
                onPressed: () {
                  // Validate will return true if the form is valid, or false if
                  // the form is invalid.
                  if (_formKey.currentState!.validate()) {
                    // Process data.
                  }
                },
                child: const Text('Submit'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}