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

void main() {
  runApp(
    const ProviderScope(child: MyApp()),
  );
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int selectedIndex = 0;
  var loadPages = [0];

  @override
  Widget build(BuildContext context) {
    print("바텀 네비게이션 클릭할때마다 전체가 다시 그려지나?");
    return Scaffold(
      body: IndexedStack(
        index: selectedIndex,
        children: [
          loadPages.contains(0) ? const APage() : Container(),
          loadPages.contains(1) ? const BPage() : Container(),
        ],
      ),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: selectedIndex,
        onTap: (index) {
          var pages = loadPages;

          if (!pages.contains(index)) {
            // 아직 열리지 않았다면!!
            pages.add(index);
            print(pages);
          }

          selectedIndex = index;
          loadPages = pages;
          setState(() {});
        },
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), label: ""),
          BottomNavigationBarItem(icon: Icon(Icons.person), label: ""),
        ],
      ),
    );
  }
}

class APage extends StatelessWidget {
  const APage();

  @override
  Widget build(BuildContext context) {
    // watch (통신)
    print("APage 통신 시작됨");

    return Center(
      child: Text("APage"),
    );
  }
}

class BPage extends StatelessWidget {
  const BPage();

  @override
  Widget build(BuildContext context) {
    // watch (통신)
    print("BPage 통신 시작됨");

    return Center(
      child: Text("BPage"),
    );
  }
}

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨
I/flutter (18404): │ 🐛 디버그 : HomePage 실행됨
I/flutter (18404): │ 🐛 디버그 : HomePage 실행됨

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨
I/flutter (18404): │ 🐛 디버그 : YourLibraryPage 실행됨
I/flutter (18404): │ 🐛 디버그 : YourLibraryPage 실행됨

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨
I/flutter (18404): │ 🐛 디버그 : ProfilePage 실행됨
I/flutter (18404): │ 🐛 디버그 : ProfilePage 실행됨

전체 ViewModel이 실행되고 나면, ViewModel은 상태를 가진 상태로 재 실행되지 않는다.

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨

I/flutter (18404): │ 🐛 디버그 : MainHolderPage 실행됨

참고

Flutter bottomNavigator with indexed stack