main.dart

import 'package:flutter/material.dart';

class Item {
  Item(this.id, this.name, this.color);
      

  final int id;
  final String name;
  final Color color;
  final int price = 42;

  @override
  int get hashCode => id;

  @override
  bool operator ==(Object other) => other is Item && other.id == id;
}

Map<int, Color> colors = {
  0: Colors.primaries[0]
};

Color genColor(int id) => Colors.primaries[id % Colors.primaries.length];

void main(){
  var a = Item(0,"", genColor(0));
  var b = Item(0,"", colors[0]??Colors.red);

}