how to make constructor in dart code example

Example 1: constructor in dart

//Creating object.
void main(){
  SelfDrivingCar myLamb = SelfDrivingCar('Floride');
  myLamb.drive();
 
}

//Initializing class Car.
class Car {
  int numberofwheels = 4;
  
  void drive() {
    print('this is a car');
  }
}

//using Inheritance 
class SelfDrivingCar extends Car {
  String destination='k';
  
  SelfDrivingCar(String userDestination){ //constructor
    destination = userDestination;
  }
  @override    //polymorphism.
  void drive() {
    super.drive();  // accessing parent's methods.
    
    print('sterring wheel to $destination');
    
  }
}

Example 2: dart constructor

void main() {
  Human jenny = Human(height1 :15);
    print(jenny.height);
  
  Human jerry = Human(height1: 20);
    print(jerry.height);
}

class Human {
  double height = 0;
  
  Human({height1 = 0}) { // constructor = initializes values of properties in the class.
    this.height = height1;
  }
  
}