dart constructor

                                    class MyClass {
  int param1;
  MyClass(this.param1);
}
final obj = MyClass(100);

class MyClassNamed {			// with named parameters
  int param1;
  MyClassNamed({required this.param1});
}
final objNamedParam = MyClassNamed(param1: 100);

                                    //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');
    
  }
}

                                    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;
  }
  
}

                                    class Customer {
  String name;
  int age;
  String location;

  // constructor
  Customer(String name, int age, String location) {
    this.name = name;
    this.age = age;
    this.location = location;
  }
}

                                    arr1 = [1, 2, 3];
arr2 = [...arr1, 4, 5, 6]
// arr -> [1, 2, 3, 4, 5, 6]