Flutter rebuild optimization

main.dart

import 'package:flutter/material.dart';

void main() {
  final app = MaterialApp(
    home: MyHomePage(),
  );
  runApp(app);
}

class Item {
  const Item(this.title, this.subtitle);

  final String title;
  final String subtitle;

  static Item createByIndex(int index) {
    return Item('Item $index', 'Subtitle $index');
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final items = List.generate(5, Item.createByIndex);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        title: Text('Rebuild Optimization'),
      ),
      body: ListView.builder(
        itemCount: items.length,
        itemBuilder: (context, index) {
          return ItemView(items[index]);
        },
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          setState(() {
            items.add(Item.createByIndex(items.length));
          });
        },
      ),
    );
  }
}

class ItemView extends StatelessWidget {
  const ItemView(this.item);

  final Item item;

  @override
  // ignore: invalid_override_of_non_virtual_member
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other is ItemView) {
      return identical(item, other.item);
    }
    return false;
  }

  @override
  // ignore: invalid_override_of_non_virtual_member
  int get hashCode => item.hashCode;

  @override
  Widget build(BuildContext context) {
    print('build ${item.title}');
    return ListTile(
      title: Text(item.title),
      subtitle: Text(item.subtitle),
    );
  }
}