Using Null Safety in classes

While you’ve seen the basics of Null Safety in the previous recipe, you should also be aware of a few rules that should drive the way you design classes in Dart.

Getting ready

Create a new pad in Dartpad and remove the default code in the main method.

How to do it...

Let's see an example of a plain Dart class, with two properties. Follow these steps:

1. Add a new class, with two strings and no value:

class Person {
  String name;
  String surname;
}

Note the compile error telling that the two fields are non-nullable

In the Person class, create a constructor that gives a value to the fields:

Person(this.name, this.surname);  

Note that the error is now fixed.

Add a named constructor, that takes a map of String, dynamic and creates an instance of Person:

Person.fromMap(Map<String, dynamic> map) {
    name = map['name'];
    surname = map['surname'];
}

Note the compile errors that shows in the console, requiring an...