Mula example

increment.dart

import 'package:flutter/material.dart';

class Increment extends StatefulWidget {
  const Increment({Key? key}) : super(key: key);

  @override
  State<Increment> createState() => _IncrementState();
}

class _IncrementState extends State<Increment> {
  late TextEditingController _controller;
  @override
  void initState() {
    _controller = TextEditingController(text: '0')
      ..addListener(() {
        setState(() {});
      });
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        TextFormField(
          controller: _controller,
          keyboardType: TextInputType.number,
        ),
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            TextButton(
              onPressed: () {
                final value =
                    int.parse(_controller.text); //convert string to int
                _controller.text = (value + 1)
                    .toString(); // increment then assign the controller value
              },
              child: const Text("Add"),
            ),
            TextButton(
              onPressed: () {
                final value =
                    int.parse(_controller.text); //convert string to int
                _controller.text = (value - 1)
                    .toString(); // decrement then assign the controller value
              },
              child: const Text("Minus"),
            ),
          ],
        )
      ],
    );
  }
}