bottom_navi_bar.dart

import 'package:flutter/material.dart';

class BottomNavigationDemo extends StatefulWidget {
  const BottomNavigationDemo({
    Key key,
    @required this.callback,
  }) : super(key: key);

  final void Function(int index) callback;

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