📌 Classes and Objects in Kotlin

In Kotlin, a class is a blueprint for creating objects. An object is an instance of a class that contains properties (variables) and methods (functions).

✅ 1. Defining a Class in Kotlin

• Classes in Kotlin are declared using the class keyword.

• It can contain properties and functions.

📌 Basic Class Example

kotlin
fun () {    val person1 = Person()    person1.name = "John"    person1.age = 25    person1.displayInfo()    val person2 = Person()    person2.name = "Emma"    person2.age = 30    person2.displayInfo()}

Output:

yaml
Name: John, Age: 25Name: Emma, Age: 30

✅ 3. Class Constructor

Primary Constructor

• Kotlin provides a concise way to declare a constructor within the class definition using the constructor keyword.

kotlin
class Person(val name: String, var age: Int) {    fun () {        println("Name: $name, Age: fun () {    val person = Person("Alice", 28)    person.displayInfo()}

Output:

yam
Name: Alice, Age: 28

• val name → Immutable property.

• var age → Mutable property.

Secondary Constructor

• You can define a secondary constructor using the constructor keyword.

kotlin
class Employee {    var name: String    var age: Int    constructor(name: String, age: Int) {        this.name = name        this.age = age    }    fun () {        println("Name: $name, Age: fun () {    val emp = Employee("David", 35)    emp.displayInfo()}

Output:

yaml
Name: David, Age: 35

✅ 4. Class Functions and Methods

Functions inside a class are called methods.

kotlin
class Calculator {    fun (a: Int, b: fun (a: Int, b: fun () {    val calc = Calculator()    println("Addition: ${calc.add(5, Addition: 8Multiplication: 24

✅ 5. Inheritance in Kotlin

Kotlin supports inheritance using the : symbol.
The parent class should be marked as open to allow inheritance.

kotlin
// Parent classopen class Animal(val name: String) {    open fun () {        println("Animal makes a sound")    }}// Child classclass Dog(name: String) : Animal(name) {    override fun () {        println("$name says Woof!")    }}fun () {    val dog = Dog("Buddy")    dog.sound()}

Output:

nginx
Buddy says Woof!

✅ 6. Object Keyword

In Kotlin, you can use the object keyword to create:

1. Singleton Objects (A single instance of a class).

2. Anonymous Objects (For one-time use).

Singleton Object

kotlin
object DatabaseConnection {    fun () {        println("Connected to the Database")    }}fun () {    DatabaseConnection.connect()}

Output:

pgsql
Connected to the Database

Anonymous Object

kotlin
interface ClickListener {    fun ()}fun () {    val buttonClick = object : ClickListener {        override fun onClick() {            println("Button clicked!")        }    }    buttonClick.onClick()}

Output:

css
Button clicked!

✅ Conclusion

• Classes define the structure of objects.

• Objects are instances of classes.

• Kotlin supports primary and secondary constructors.

• Use open for inheritance and override for method overriding.

• Use object for creating singletons or anonymous objects.