Diferença entre stateless e stateful widget no Flutter

Diferença entre stateless e stateful widget no Flutter | Alura Cursos Online

Align(
	alignment: Alignment.center,
	child: MeuWidget(
		width: 300,
		height: 455,
		decoration: BoxDecoration(
			color: Colors.white,
			borderRadius: BorderRadius.circular(12)
		),
	),
),

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}
class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Alura Stateless'),
      ),
      body: Center(
        child: Text(
          'Alura Stateless',
          style: TextStyle(
            fontSize: 30,
            fontWeight: FontWeight.bold,
          ),
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';
class MeuWidget extends StatefulWidget {
  @override
  _MeuWidgetState createState() => _MeuWidgetState();
}
class _MeuWidgetState extends State<MeuWidget> {
  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

import 'package:flutter/material.dart';
void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Alura Stateful'),
    );
  }
}
class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
  int _contador = 0;
  void _incrementarContador() {
    setState(() {
      _contador++;
    });
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              '$_contador',
              style: Theme.of(context).textTheme.headline4,
            ),
            SizedBox(height: 20,),
            RaisedButton(
              child: Text(
                'Adicionar +1',
                style: TextStyle(
                  fontSize: 18,
                  color: Colors.white,
                ),
              ),
              onPressed: _incrementarContador,
              color: Theme.of(context).primaryColor,
            ),
            SizedBox(height: 10,),
            RaisedButton(
              child: Text(
                'Zerar',
                style: TextStyle(
                  fontSize: 18,
                  color: Colors.white,
                ),
              ),
              onPressed: () {
                setState(() {
                  _contador = 0;
                });
              },
              color: Theme.of(context).primaryColor,
            ),
          ],
        ),
      ),
    );
  }
}

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Diferença entre stateless e stateful widget no Flutter

Leonardo Marinho

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Widgets

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Stateless widgets

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Leonardo Marinho

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Widgets

Estados

Stateless widgets

Stateful widgets

Como aprender mais sobre Flutter

Conclusão

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