Classes, constructors, mixins and enums

Flutter apps describe their data with small immutable classes, which never change after creation. They have final fields, a const constructor, and a copyWith method that returns a changed copy instead of editing the original. Learn the constructor shorthand (this.title), named constructors such as User.fromJson, and factory constructors.

Learn to override == and hashCode, so two users with the same id count as equal. A mixin adds reusable behaviour to a class with the with keyword. An enum lists a fixed set of options, and Dart enums can hold fields and methods too.