【 Flutter 】Flutter を 基礎 から 学習 ( ウィジェット編 ) part67 Multi-child layout widgets

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(home: new MyApp()));
}

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _State();
  }
}

class _State extends State<MyApp> {
  int _index = 0;
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
      appBar: AppBar(
        title: Text('テスト中です。'),
      ),
      body: IndexedStack(
        index: _index,
        children: <Widget>[
          box(
            color: Colors.black,
          ),
          box(
            color: Colors.red,
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() {
            if (_index == 0) {
              _index = 1;
            } else {
              _index = 0;
            }
          });
        },
      ),
    ));
  }

  Widget box(
      {double height = 50,
      double width = 50,
      Color color = Colors.green,
      String txt = "0"}) {
    return Container(
        margin: const EdgeInsets.all(2),
        height: height,
        width: width,
        color: color,
        child: Text(txt));
  }
}