dartでのinstance評価と演算子オーバーロード

main.dart

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class TestObject {
  final int id;
  final String value;
  TestObject(this.id, this.value);
}

class TestObject2 {
  final int id;
  final String value;
  TestObject2(this.id, this.value);

  @override
  bool operator==(other) {
    if(other is! TestObject2) {
      return false;
    }
    return id == (other as TestObject2).id;
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text(valueChecker(), style: Theme.of(context).textTheme.headline4);
  }
  
  
  String valueChecker() {
//     final a = TestObject(1, 'a');
//     final b = TestObject(1, 'a');
     final a = TestObject2(1, 'a');
     final b = TestObject2(1, 'b');
    
    if (a == b) {
      return "same";
    } else {
      return "different";
    }
  }
}