CODEWITHSUNDEEP
dart
Dmitry Bubnenkov
Dmitry Bubnenkov

Reputation: 9859

Can I use class without constructor?

I am learning Dart. I did not found any answer for my question in docs. Can I create and use class without constructor, or I can get some problem with it later?

class MyClass {
  String name;
  int age;
}

Upvotes: 1

Views: 1845

Answers (2)

Stijn2210
Stijn2210

Reputation: 884

Sure, you don’t have to use a constructor in your class, but that takes away your ability to create an immutable class with final fields plus you can’t set your values instantly. There will always be a default constructor for your class without you defining it. With your current code you’d have to do something like

final myVar = MyClass();
myVar.name = "John";
myVar.age = 24;

Upvotes: 2

lrn
lrn

Reputation: 71693

You can create an use a class with no explicit constructor.

If you do not write any constructor, you will be given a default constructor of MyClass() : super();. That only works if

  • Your class has no final fields without initializer expressions.
  • Your superclass has an unnamed generative constructor which can be called with no arguments (which Object satisfies.)

It means that your get a public generative constructor, which allows others to extend your class. If you want to prevent that, you can change that to a public factory/private generative constructor pair:

  factory C() => C._();
  C._();

Upvotes: 5

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