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What are Classes and Objects?

In Dart, a class is a blueprint for creating objects. It defines the properties (attributes) and behaviors (methods) that objects of that class will have. Think of a class as a template or a cookie cutter, while objects are the actual cookies produced using that template.

For example, let's consider a class called Person, which might have properties like name, age, and gender, along with methods like greet() or calculateAge(). Each person in our program would be an object instantiated from the Person class.

Creating Classes in Dart

In Dart, defining a class is straightforward. Here's a simple example:

 class Person { 
String name; int age; // Constructor Person(this.name, this.age); 
// Method to greet 
void greet() { print("Hello, my name is $name and I am $age years old."); } 
} 

In the above code, we've defined a Person class with two properties: name and age. We've also included a constructor to initialize these properties when creating a new Person object, and a greet() method to display a greeting message.

Creating Objects in Dart

Once we've defined a class, we can create objects from it using the new keyword:

In this example, we've created a Person object named person1 with the name "Alice" and age 30, and then we've called the greet() method on it to display a greeting message.

Everthing in one umbrella with examples

//Classes and objects  --DART  PART 3

// Blue print of real life

//We need a data type that can define real life objects structure
// data + Functions collection
//purpose : so that I can reuse that data type/structure as per requirement

class Calculator {
  // Curly baraced : Scope of the class : Body of the class

  int a = 10; //Global variables in terms of functions

  void sum() {
    print(a+2);
  }
  void divide() {
    print(a/2);
  }

}

void main() {
//How to create object of the class;
//Why object : to access class data we need objects
//What are objects:
//Ans : Objects are actually copy/snapshot of class
//so that we can access class operations.

//Objects are memory location in ram for each object
//New keyowrd : is used to assign memory to that object

   // Calculator ob1 = new Calculator();
   //  Calculator ob1 =  Calculator();
     var ob1 =  Calculator();
     ob1.a=100;
   ob1.sum();
   ob1.divide();



  /*
  -Number
  -- int
  -- double
   */
//int and String are pre built keywords

//Contain one value at a time
  int age = 56;
  //print("age=${age}");
  // print('age=${age}');
  double percentage = 90.56;

  String name = "Techmalasi";
  String movie = 'Captain America';

  //Contcate variables with strings
  // print("The movie name=${movie}");
  //Is Ankit a Topper of the class.
  // Yes OR No
  bool isTopper = true; //1
  bool isRainny = false; //0
  // print(isTopper);

  //Collection in Dart
  //What are you list of fav movies?
  //Array : collection of something
  /*
  - Collection
  -- List : an Array
  -- Set  : an Array without duplicate values
  -- Map : It is just like JSON DATA - Key value pairs
   */

  // Loose Type : Typed not checked
  // List movies =["DDLJ",45.78,true,"Captain America","Sholay","Iron Man",30];

  //Strict Type : Type checked

// List <String>movies =["DDLJ","Captain America","Sholay","Iron Man"];

// List movies =<String>["DDLJ","Captain America","Sholay","Iron Man"];
//
//
//
//   print(movies);

  //Duplicates allowed
  // List numbers=[3,5,7,3,45,3];
  // print(numbers);

  // Set numbers ={3,5,7,3,8,3,45.67}; //Map/Set
  //  print(numbers);

  // Set <int>numbers ={3,5,7,3,8,3}; //Map/Set
  // print(numbers);

  // Set p1 = Set();
  // p1.add("5");
  //
  // print(p1);

  //MAP

  // Map student={
  //     "name" :"Techmalasi", //String
  //   "age" : 40, // int
  //   "percentage":90.45 // double
  //
  // };

  //
  // Map <String,dynamic>student={
  //    "name" :"Techmalasi", //String
  //   "age" : 40, // int
  //   "percentage":90.45 // double
  //
  // };
  // print(student);

//variable type
  var age2 = 45.67;
  var name2 = "kamal";
  var movies = ['a', "ddlj"];
//As per input type , Data Tpye is defined
}

Conclusion

Understanding classes and objects is essential for anyone learning Dart or any object-oriented programming language. With classes, you can create reusable and organized code, making your applications easier to maintain and extend. In Dart, creating classes and objects is simple yet powerful, allowing you to build complex applications with ease. So dive in, explore, and start building amazing things with Dart!