How to create classes and objects in Dart

Dart is an object-oriented programming language, which means it supports concepts like classes, objects, etc.

Classes

Classes are the blueprints of objects. A class is a blueprint from which a variety of objects can be created. All properties and methods of the class will be accessible to all objects.

Syntax for class declaration

class class_name {

   // Body of class
}

Here, class is the keyword used to initialize the class.

The class_name is the name of the class. The body of the class will consist of properties, constructors, getters and setters, methods, etc.

Objects

Objects are instances of a class, and they are declared with the new keyword and the class name.

Syntax for object declaration

syntax:
var object_name = new class_name([ arguments ]);

Here:

  • new is the keyword that is used to declare an instance of the class.
  • object_name is the object’s name.
  • class_name is the name of the class whose instance variable is being generated.
  • arguments are the parameters that must be sent if a constructor is to be called.

To access the properties and methods of the class, we use the object’s name with the dot (.) operator.

// For accessing the property
object_name.property_name;

// For accessing the method
object_name.method_name();

Code

// Creating Class Student
class Student {
 
    // creating properties
    String name;
    String roll_number;
    String course;
    String level;
 
    // Creating Function 
    void registerCourse()
    {
        print("$roll_number registered for CSC 101");
    }
    void record(){
      print('$name with $roll_number is studying $course');
    }
}
 
void main()
{
    // Creating Instance of class
    Student s1 = new Student();
    //creating another object
    Student s2 = new Student();
    // Calling property roll_number and assigning value
    // to it using object of the class student
    s1.roll_number = '195HQ024';
    s2.name = 'Maria';
    s2.roll_number = '195HQ045';
    s2.course = 'Computer science';
    // Calling function 
    s1.registerCourse();
    s2.record();
}

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