[Flutter/Project](Instagram Clone) BottomNavigationBar

// main.dart

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

void main() {
  runApp(MyApp());
}

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

// home_page.dart

import 'package:flutter/material.dart';

class HomePage extends StatefulWidget {
  HomePage({
    Key key,
  }) : super(key: key);

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

class _HomePageState extends State<HomePage> {
  List<BottomNavigationBarItem> btmNavItems = [
    BottomNavigationBarItem(icon: Icon(Icons.home), label: ""),
    BottomNavigationBarItem(icon: Icon(Icons.search), label: ""),
    BottomNavigationBarItem(icon: Icon(Icons.add), label: ""),
    BottomNavigationBarItem(icon: Icon(Icons.healing), label: ""),
    BottomNavigationBarItem(icon: Icon(Icons.account_circle), label: ""),
  ];

  // 바텀네비게이션 바의 인덱스
  int _selectedIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        color: Colors.amber,
      ),
      bottomNavigationBar: BottomNavigationBar(
        unselectedItemColor: Colors.grey,
        selectedItemColor: Colors.black,
        showSelectedLabels: false /* 레이블 비활성화 */,
        items: btmNavItems /* List<BottomNavigationBarItem> 리스트 타입의 데이터 */,
        currentIndex: _selectedIndex,
        onTap: _onBtmItemClick,
      ),
    );
  }

  void _onBtmItemClick(int index) {
    setState(() {
      // onTap으로 상태가 변경될 때 마다 setState로 상태를 새로 불러온다.
      _selectedIndex = index;
    });
  }
}