Enum Classes in Kotlin

Introduction

Enum Classes is a fundamental concept every Kotlin developer should understand. Object declarations and companion objects provide singletons, factory methods, and static-like members without the ceremony of Java static blocks.

Enum class represents a fixed set of constants. In this tutorial you will learn the syntax, walk through a complete example program, study the sample output, and review best practices so you can apply the concept confidently in your own projects.

Definition

• enum class represents a fixed set of constants.
• Each enum constant is an object.
• Enums can have properties and functions.

Syntax

enum class Level { LOW, MEDIUM, HIGH }

Enum Classes in Kotlin Example Program in Kotlin

enum class Status(val label: String) {
    SUCCESS("Success"),
    FAILED("Failed")
}

fun main(args: Array<String>) {
    val status = Status.SUCCESS
    println(status.label)
}

Sample Output

Success

When to use

Use object for true singletons; use companion object for factory methods and constants tied to a class.

How it works

1. The program starts with a main function — the entry point that runs when you execute the file.

2. val status = Status.SUCCESS assigns or updates a value used later in the program.

3. The println(status.label) statement writes a line to the console — this produces part of the sample output below.

4. Enum class represents a fixed set of constants.

5. Run the program in IntelliJ IDEA, Android Studio, or with the Kotlin command-line compiler (kotlinc / kotlin). Compare your console output with the sample output shown below.

Best Practices

Common Mistakes

Key Points

• enum class represents a fixed set of constants.
• Each enum constant is an object.
• Enums can have properties and functions.
• Test the example locally and verify the output matches the sample.
• Experiment by changing input values to see how behaviour changes.

Notes

• Semicolons at the end of statements are optional in Kotlin.