👨‍🏫0.5 TextFormField() controller

import 'package:flutter/material.dart';

class Lesson18 extends StatefulWidget {
  const Lesson18({super.key});

  @override
  State<Lesson18> createState() => _Lesson18State();
}

class _Lesson18State extends State<Lesson18> {
  TextEditingController titleController = TextEditingController();

  String title = 'Hello';
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          crossAxisAlignment: .start,
          children: [
            Text(title, style: TextStyle(fontSize: 40),),
            TextFormField(
              controller: titleController,
              decoration: InputDecoration(
                border: OutlineInputBorder()
              ),
            ),

            ElevatedButton(onPressed: (){
              setState(() {
                title = titleController.text!;
              });
            }, child: Text('Apply'))
          ],
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class Lesson18 extends StatefulWidget {
  const Lesson18({super.key});

  @override
  State<Lesson18> createState() => _Lesson18State();
}

class _Lesson18State extends State<Lesson18> {
 
  TextEditingController numberController = TextEditingController();

  

  int number = 12;
  double numberTwo = 34.98;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          crossAxisAlignment: .start,
          children: [
            

            Text('$number', style: TextStyle(fontSize: 40),),
            TextFormField(
              controller: numberController,
              decoration: InputDecoration(
                  border: OutlineInputBorder()
              ),
            ),

            ElevatedButton(onPressed: (){
              setState(() {
                number = int.tryParse(numberController.text)!;
                numberTwo = double.tryParse(numberController.text)!;
              });
            }, child: Text('Apply')),
          ],
        ),
      ),
    );
  }
}

class Lesson18a extends StatefulWidget {
  const Lesson18a({super.key});

  @override
  State<Lesson18a> createState() => _Lesson18aState();
}

class _Lesson18aState extends State<Lesson18a> {
  TextEditingController aController = TextEditingController();
  TextEditingController bController = TextEditingController();

  // =, +=, -=, *=, /=
  // +, -, *, /
  int number = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            Text('$number', style: TextStyle(fontSize: 40),),
            Row(
              spacing: 20,
              children: [
                Expanded(child: TextFormField(
                  controller: aController,
                  decoration: InputDecoration(
                    border: OutlineInputBorder()
                  ),
                )),
                Expanded(child: TextFormField(
                  controller: bController,
                  decoration: InputDecoration(
                    border: OutlineInputBorder()
                  ),
                ))
              ],
            ),
            ElevatedButton(onPressed: (){
              setState(() {
                number = int.tryParse(aController.text)! + int.tryParse(bController.text)!;
              });
            }, child: Text('+', style: TextStyle(fontSize: 40),))
          ],
        ),
      ),
    );
  }
}

class Lesson18bread extends StatefulWidget {
  const Lesson18bread({super.key});

  @override
  State<Lesson18bread> createState() => _Lesson18breadState();
}

class _Lesson18breadState extends State<Lesson18bread> {
  TextEditingController countController = TextEditingController();

  double eggs = 1;
  double water = 0.5;


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          spacing: 50,
          children: [
            Row(
              children: [
                Expanded(
                  child: TextFormField(
                    controller: countController,

                  ),
                ),
                Text('ШТ')
              ],
            ),
            
            ElevatedButton(onPressed: (){
              setState(() {
                water *= double.tryParse(countController.text)!;
                eggs *= double.tryParse(countController.text)!;
              });
            }, child: Text('Save')),
            Container(
              height: 200,
              width: double.infinity,
              decoration: BoxDecoration(
                color: Colors.green.shade100
              ),
              child: Column(
                children: [
                  Text('$eggs яйца'),
                  Text('$water литр воды'),

                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}