flutter: checking init/dispose for TabView

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static List<Widget> tabsContent = [
    AddContent(),
    RemoveContent(),
    RefreshContent(),
    CopyContent()
  ];

  static List<Tab> tabs = [
    Tab(
      icon: Icon(Icons.add),
    ),
    Tab(
      icon: Icon(Icons.delete),
    ),
    Tab(
      icon: Icon(Icons.refresh),
    ),
    Tab(
      icon: Icon(Icons.content_copy),
    )
  ];

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: tabs.length,
      child: Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
          bottom: TabBar(tabs: tabs),
        ),
        body: TabBarView(children: tabsContent),
      ),
    );
  }
}

class AddContent extends StatefulWidget {
  @override
  _AddContentState createState() => _AddContentState();
}

class _AddContentState extends State<AddContent> {
  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[Text("add")],);
  }

  @override
  void dispose() {
    print("add dispose");

    super.dispose();
  }

  @override
  void initState() {
    super.initState();

    print("add init");
  }
}

class RemoveContent extends StatefulWidget {
  @override
  _RemoveContentState createState() => _RemoveContentState();
}

class _RemoveContentState extends State<RemoveContent> {
  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[Text("remove")],);
  }

  @override
  void dispose() {
    print("remove dispose");

    super.dispose();
  }

  @override
  void initState() {
    super.initState();

    print("remove init");
  }
}

class RefreshContent extends StatefulWidget {
  @override
  _RefreshContentState createState() => _RefreshContentState();
}

class _RefreshContentState extends State<RefreshContent> {
  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[Text("refresh")],);
  }

  @override
  void dispose() {
    print("refresh dispose");

    super.dispose();
  }

  @override
  void initState() {
    super.initState();

    print("refresh init");
  }
}

class CopyContent extends StatefulWidget {
  @override
  _CopyContentState createState() => _CopyContentState();
}

class _CopyContentState extends State<CopyContent> {
  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[Text("copy")],);
  }

  @override
  void dispose() {
    print("copy disposed");

    super.dispose();
  }

  @override
  void initState() {
    super.initState();

    print("copy init");
  }
}