Enums in Java

An enum is a special Java type for a fixed set of related constants. Use an enum when a value should be one of a known, limited set of choices.

For example, the days of the week are a fixed set of values.

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

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Why Use Enums?

Enums make code clearer and safer than using strings or numbers for fixed choices.

String status = "ACTIVE";

The string can contain a typo or an unexpected value. An enum restricts the value to valid choices.

enum Status {
    ACTIVE, INACTIVE, SUSPENDED
}

Status status = Status.ACTIVE;

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Using Enum Values

Refer to an enum value with the enum type followed by a dot.

enum Size {
    SMALL, MEDIUM, LARGE
}

public class Main {
    public static void main(String[] args) {
        Size selectedSize = Size.MEDIUM;

        System.out.println(selectedSize); // MEDIUM
    }
}

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values() and valueOf()

Every enum provides useful built-in methods.

values() returns all constants in declaration order.

for (Size size : Size.values()) {
    System.out.println(size);
}

valueOf() converts the exact name of a constant into an enum value.

Size size = Size.valueOf("LARGE");

System.out.println(size); // LARGE

If the name does not match a constant, valueOf() throws IllegalArgumentException.

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Enums with switch

Enums work naturally with switch statements.

enum OrderStatus {
    NEW, PAID, SHIPPED, DELIVERED
}

OrderStatus status = OrderStatus.SHIPPED;

switch (status) {
    case NEW:
        System.out.println("Order created");
        break;
    case PAID:
        System.out.println("Payment received");
        break;
    case SHIPPED:
        System.out.println("Order is on the way");
        break;
    case DELIVERED:
        System.out.println("Order delivered");
        break;
}

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Enums Can Have Fields and Methods

An enum can contain fields, constructors, and methods. This is useful when each constant needs extra data.

enum Plan {
    FREE(0),
    BASIC(299),
    PREMIUM(799);

    private final int monthlyPrice;

    Plan(int monthlyPrice) {
        this.monthlyPrice = monthlyPrice;
    }

    int getMonthlyPrice() {
        return monthlyPrice;
    }
}

public class Main {
    public static void main(String[] args) {
        Plan plan = Plan.BASIC;

        System.out.println(plan.getMonthlyPrice()); // 299
    }
}

Enum constructors are implicitly private. You cannot create enum values with new.

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Comparing Enums

Compare enum values with ==.

Status currentStatus = Status.ACTIVE;

if (currentStatus == Status.ACTIVE) {
    System.out.println("Account is active");
}

== is safe because each enum constant is a single shared object.

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A Practical Example

enum AccessLevel {
    GUEST, MEMBER, ADMIN
}

public class AccessService {
    static boolean canDeleteUsers(AccessLevel level) {
        return level == AccessLevel.ADMIN;
    }

    public static void main(String[] args) {
        AccessLevel userLevel = AccessLevel.MEMBER;

        System.out.println(canDeleteUsers(userLevel)); // false
    }
}

The method accepts only a valid access level, so invalid strings such as "ADMNI" cannot slip into the program.

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When to Use Enums

Enums are a good fit for:

• Status values, such as pending or completed
• User roles and access levels
• Days, months, directions, and sizes
• Fixed application settings or categories
• Options used in switch statements

Use a regular class when the set of possible values is created dynamically at runtime.