In Kotlin, an abstract class is a class that cannot be instantiated directly. It is designed to be a base class for other classes, providing common functionality and defining abstract methods that must be implemented by subclasses.

✅ Key Features of Abstract Classes in Kotlin

1. Abstract Declaration:

   • Use the abstract keyword to declare an abstract class or abstract method.

2. No Instantiation:

   • You cannot create objects of an abstract class.

3. Concrete and Abstract Members:

   • Abstract classes can have both concrete (implemented) and abstract (unimplemented) methods.

4. Inheritance:

   • Subclasses must implement all abstract members unless they are abstract themselves.

📌 Syntax Example

kotlin
abstract class Shape {    abstract fun ()    fun () {        println("Displaying the shape")    }}// Subclass implementing abstract classclass Circle : Shape() {    override fun () {        println("Drawing a Circle")    }}fun () {    val circle = Circle()    circle.draw()        // Output: Drawing a Circle    circle.display()     // Output: Displaying the shape}

⚡ Explanation

1. abstract class Shape → Shape is an abstract class with an abstract method draw().

2. fun display() → A concrete method available for all subclasses.

3. class Circle : Shape() → Subclass overrides and implements the draw() method.

4. circle.display() → Calls the non-abstract method from the parent class.

🔎 Abstract Properties

Abstract classes can also have abstract properties that must be overridden in subclasses.

kotlin
abstract class Animal {    abstract val sound: String    abstract fun ()}class Dog : Animal() {    override val sound: String = "Bark"    override fun () {        println("Dog goes $sound")    }}fun main() {    val dog = Dog()    dog.makeSound()  // Output: Dog goes Bark}

🚀 When to Use Abstract Classes

• When you want to create a base class with shared functionality.

• When certain methods or properties must be implemented by subclasses.

• When objects of the base class should not be directly instantiated.

If you need further clarification or examples, feel free to ask!