Enum with properties and methods in Kotlin - Mini Project: Build & Apply

Enum with properties and methods

📖 Scenario: Imagine you are creating a simple app that shows different types of coffee sizes with their prices and descriptions.

🎯 Goal: You will create an enum class in Kotlin that has properties and a method to describe each coffee size.

📋 What You'll Learn

Create an enum class called CoffeeSize with three entries: SMALL, MEDIUM, and LARGE

Each enum entry should have two properties: price (Double) and description (String)

Add a method called displayInfo() inside the enum that returns a string combining the size name, price, and description

Print the result of calling displayInfo() on each enum entry

💡 Why This Matters

🌍 Real World

Enums with properties and methods are useful to represent fixed sets of related data with extra details, like product sizes, statuses, or categories.

💼 Career

Understanding enums with properties and methods helps in writing clean, organized code in Kotlin, which is valuable for Android development and backend services.

1

Create the enum class with entries and properties

Create an enum class called CoffeeSize with three entries: SMALL, MEDIUM, and LARGE. Each entry should have two properties: price of type Double and description of type String. Use the exact values: SMALL(2.5, "Small cup"), MEDIUM(3.5, "Medium cup"), LARGE(4.5, "Large cup").

Kotlin

enum class CoffeeSize(val price: Double, val description: String) {
    // Your code here
}

Need a hint?

Remember to declare the properties inside the parentheses after the enum name and separate entries with commas.

2

Add a method to display info

Inside the CoffeeSize enum class, add a method called displayInfo() that returns a String. This method should return a string in the format: "Size: [name], Price: $[price], Description: [description]". Use the enum's name property for the size name.

Kotlin

enum class CoffeeSize(val price: Double, val description: String) {
    SMALL(2.5, "Small cup"),
    MEDIUM(3.5, "Medium cup"),
    LARGE(4.5, "Large cup")

    // Your code here
}

Need a hint?

Use the name property of the enum to get the size name. Use string templates with $ to insert values.

3

Call the method for each enum entry

Write a main function. Inside it, use a for loop with variable size to iterate over CoffeeSize.values(). For each size, call displayInfo() and store the results in a list called infoList.

Kotlin

fun main() {
    val infoList = mutableListOf()
    // Your code here
}

Need a hint?

Use CoffeeSize.values() to get all enum entries. Add each displayInfo() result to infoList.

4

Print the info list

In the main function, after the loop, print each string in infoList on its own line using a for loop with variable info.

Kotlin

enum class CoffeeSize(val price: Double, val description: String) {
    SMALL(2.5, "Small cup"),
    MEDIUM(3.5, "Medium cup"),
    LARGE(4.5, "Large cup")

    fun displayInfo(): String {
        return "Size: $name, Price: $$price, Description: $description"
    }
}

fun main() {
    val infoList = mutableListOf()
    for (size in CoffeeSize.values()) {
        infoList.add(size.displayInfo())
    }
    for (info in infoList) {
        // Your code here
    }
}

Need a hint?

Use println(info) inside the loop to print each string on its own line.