dart class constructor code example

Example 1: dart this 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);

Example 2: class in dart

class class_name {  
	//rest of the code here:
}

Example 3: 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 4: dart call constructor in constructor

class Chipmunk {
  String name;
  int fame;

  Chipmunk.named(this.name, [this.fame]);

  Chipmunk.famous1() : this.named('Chip', 1000);
  factory Chipmunk.famous2() {
    var result = new Chipmunk.named('Chip');
    result.fame = 1000;
    return result;
  }
}

Example 5: Flutter Constructor

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

Customer(this.name, this.age) {
  this.name = name;
  this.age = age;
}

Example 6: dart ?? operator

int val1;
final int val2 = 20;

console.log(val1 ?? val2); //result => 20 because val1 is null

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final int val1 = 30;
final int val2 = 20;

console.log(val1 ?? val2); //result => 30 because val1 is not null