Enums (short for enumerations) are a powerful yet underappreciated feature in object-oriented design. They allow you to define a fixed set of named constants that improve clarity, type safety, and maintainability in your system.

Used correctly, enums can make your code more expressive, self-documenting, and resilient to errors.

What is an Enum?

An enum is a special data type that defines a collection of constant values under a single name. Unlike primitive constants or string literals, enums are type-safe, you can’t assign just any value to a variable declared as an enum type.

Enums are perfect when a variable can only take one out of a small set of predefined values.

Example Enums

• States (e.g., PENDING, IN_PROGRESS, COMPLETED)
• Roles (e.g., ADMIN, CUSTOMER, DRIVER)
• Vehicle Types (e.g., CAR, BIKE, TRUCK)
• Directions (e.g., NORTH, SOUTH, EAST, WEST)

Enums help avoid magic strings or numbers, improve readability, enable compiler checks, IDE auto-completion and reduce bugs caused by invalid values.

Examples

Simple Enum

Enum representing status of an order in an e-commerce application.

This defines a clear set of valid statuses for an order.

Using it in code:

Enums with Properties and Methods

Enums can have additional data and even behavior. This makes them even more powerful.

Coin Enum with Denomination

Usage:

This is far more elegant and safe than using integers directly.