Delegation vs inheritance decision in Kotlin - Hands-On Comparison

Delegation vs Inheritance Decision in Kotlin

📖 Scenario: Imagine you are building a simple app to manage different types of workers in a company. Some workers have special skills, and you want to reuse code efficiently. You will learn when to use inheritance and when to use delegation in Kotlin.

🎯 Goal: You will create classes using inheritance and delegation to share behavior. Then you will decide which approach fits better by comparing outputs.

📋 What You'll Learn

Create a base class with a common function

Create a subclass using inheritance

Create a class using delegation to reuse behavior

Print outputs from both inheritance and delegation examples

💡 Why This Matters

🌍 Real World

In real apps, choosing between inheritance and delegation helps keep code flexible and easier to maintain.

💼 Career

Understanding these concepts is important for Kotlin developers working on clean, reusable code in Android or backend projects.

1

Create a base class with a common function

Create a Kotlin class called Worker with a function work() that returns the string "Working hard".

Kotlin

# Create the Worker class with work() function
// Your code here

Need a hint?

Define a class named Worker and inside it a function work() that returns the exact string "Working hard".

2

Create a subclass using inheritance

Create a class called Manager that inherits from Worker. Override the work() function to return "Managing team".

Kotlin

open class Worker {
    open fun work(): String {
        return "Working hard"
    }
}

// Create Manager class inheriting Worker and override work()
// Your code here

Need a hint?

Use class Manager : Worker() to inherit. Use override fun work() to change the behavior.

3

Create a class using delegation to reuse behavior

Create a class called Assistant that takes a Worker object as a constructor parameter and delegates the work() function to it. Use Kotlin's by keyword for delegation.

Kotlin

open class Worker {
    open fun work(): String {
        return "Working hard"
    }
}

class Manager : Worker() {
    override fun work(): String {
        return "Managing team"
    }
}

// Create Assistant class delegating work() to Worker
// Your code here

Need a hint?

Define class Assistant(private val worker: Worker) : Worker by worker to delegate using the by keyword.

4

Print outputs from inheritance and delegation examples

Create instances of Manager and Assistant (passing a Worker to it). Print the results of calling work() on both instances.

Kotlin

open class Worker {
    open fun work(): String {
        return "Working hard"
    }
}

class Manager : Worker() {
    override fun work(): String {
        return "Managing team"
    }
}

class Assistant(private val worker: Worker) : Worker by worker

// Create Manager and Assistant instances and print their work() results
// Your code here

Need a hint?

Create val manager = Manager() and val assistant = Assistant(Worker()). Then print manager.work() and assistant.work().