Defining enums
- Dart course
- Beginner
- Lesson 94/116
- 4 min
Learn to define named constants with enum.
What is an enum?
An enum is a set of named constants. It groups a limited number of options under a single type. For example days of the week, order status, traffic light colors. Grouping constants in an enum instead of writing them one by one makes code readable and safe.
In Dart the definition is: enum Color { red, green, blue }. Each name is a constant; you access it as Color.red. It gives type safety: a function expecting a Color cannot accidentally take a String. The order of the constants follows the order they are written.
Defining an enum
To define an enum you write the enum keyword, then a name and a list of constants inside curly braces. Constants are separated by commas and conventionally start with lowercase. enum Heat { low, medium, high } is a valid definition.
After the definition you can assign a constant to a variable: final h = Heat.medium;. The compiler catches a wrong constant name right away; Heat.tallness would not compile. That is why enum is safer than string constants. The dot also gives you autocomplete when you type the constant name.
Practice Your turn: define a Color enum
Define an enum called Color with constants red, green and blue. In main assign Color.green to a variable and print it.
Starter code
void main() {
// Define a Color enum
// Assign a constant and print
}Sample solution
enum Color { red, green, blue }
void main() {
final c = Color.green;
print(c);
}Expected output
Color.green
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is enum best suited for?
- Heavy numeric computation
- Random text input
- A limited set of named options Correct answer
- File operations
Explanation: enum is for a limited set of named options.
2 The enum keyword
____ Color { red, green, blue }enum Color { red, green, blue }Explanation: The enum keyword starts the definition.
3 Match enum
| Term | Meaning |
|---|---|
enum |
named constants |
Color.red |
a single constant |
{ ... } |
the constant list |
enum keyword |
starts the definition |