How to Create Enum in Java: Syntax and Examples

In Java, you create an enum by using the enum keyword followed by the name and a list of constant values inside curly braces. Enums represent a fixed set of constants and can be used like classes with methods and fields.

Syntax

An enum is declared using the enum keyword followed by the enum name and a list of constants separated by commas inside curly braces.

• enum: keyword to define an enum type
• Name: the name of the enum type (like a class name)
• Constants: fixed values separated by commas

java

public enum Day {
    SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}

Example

This example shows how to create an enum Day and use it in a simple program to print a message based on the day.

java

public class EnumExample {
    public enum Day {
        SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
    }

    public static void main(String[] args) {
        Day today = Day.WEDNESDAY;

        switch (today) {
            case MONDAY:
                System.out.println("Start of the work week.");
                break;
            case FRIDAY:
                System.out.println("Almost weekend!");
                break;
            case SATURDAY:
            case SUNDAY:
                System.out.println("It's the weekend!");
                break;
            default:
                System.out.println("Midweek day.");
                break;
        }
    }
}

Output

Midweek day.

Common Pitfalls

Common mistakes when creating enums include:

• Not using uppercase letters for enum constants (by convention, constants are uppercase).
• Trying to assign values directly like variables (enums are constants).
• Forgetting the semicolon when adding fields or methods after constants.
• Using enums without understanding they are types, not just constants.

java

/* Wrong: enum constants should be uppercase and no assignment */
public enum Color {
    red = 1, green = 2, blue = 3; // This is invalid
}

/* Right way: */
public enum Color {
    RED, GREEN, BLUE;
}

Quick Reference

Feature	Description
Declaration	Use enum Name { CONSTANT1, CONSTANT2, ... }
Constants	Fixed set of named values, usually uppercase
Usage	Enums can be used in switch statements and comparisons
Methods	Enums can have fields, constructors, and methods
Convention	Enum names are PascalCase, constants are UPPERCASE

Key Takeaways

Use the enum keyword to define a fixed set of constants in Java.

Enum constants are usually written in uppercase letters by convention.

Enums can be used in switch statements for clear, readable code.

You can add fields and methods to enums for more complex behavior.

Remember to use enums as types, not just as simple constants.