classes dart code example

Example 1: class in dart

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

Example 2: 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

Example 3: with keyword in dart

mixin Human {
  String name;
  int age;

  void about();
}

class Doctor with Human {
  String specialization;
  Doctor(String doctorName, int doctorAge, String specialization) {
    name = doctorName;
    age = doctorAge;
    this.specialization = specialization;
  }

  void about() {
    print('$name is $age years old. He is $specialization specialist.');
  }
}


void main() {
  Doctor doctor = Doctor("Harish Chandra", 54, 'child');
  print(doctor.name);
  print(doctor.age);
  doctor.about();
}

Example 4: dart class

// entry point
void main(){

  // using the Dog class - creating an instance of this class
  var myDog = Dog();
  
  // assigning values to the newly clreated instance
  myDog.breed = 'Poodle';
  myDog.name = 'Jack';
  myDog.color = 'Brown';
 
  // displaying the values on the console 
  print(myDog.breed);
  print(myDog.name);
  print(myDog.color);
}

// Dog class 
class Dog{

  // class properties
  String breed;
  String name;
  String color;
}