Singleton

Singleton.dart

class SingletonOne {
  SingletonOne._privateConstructor();
  static final _instance = SingletonOne._privateConstructor();
  factory SingletonOne() {
    return _instance;
  }
}

class SingletonTwo {
  SingletonTwo._privateConstructor();
  static final _instance = SingletonTwo._privateConstructor();
  static SingletonTwo get instance => _instance;
}

class SingletonThree {
  SingletonThree._privateConstructor();
  static final instance = SingletonThree._privateConstructor();
}

void main() {

  SingletonOne one = SingletonOne();
  SingletonTwo two = SingletonTwo.instance;
  SingletonThree three = SingletonThree.instance;

  print(one);
  print(two);
  print(three);

}