Enums in Switch Statements

One of the best places to use an Enum is inside a switch statement.

Because the compiler knows exactly what all the possible values of an enum are, using them in switch statements makes your code incredibly clean, readable, and perfectly type-safe.

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Example: Switch Case with Enums

When you pass an enum variable into a switch statement, you do not need to prefix the case labels with the enum type name. You just use the constant name directly (e.g., MONDAY, not Day.MONDAY).

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

public class LabEnumSwitch1 {

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

    // Passing the enum directly into the switch statement
    switch (today) {
      case MONDAY:
        System.out.println("Start of the work week.");
        break;
      case FRIDAY:
        System.out.println("TGIF! Almost the weekend.");
        break;
      case SATURDAY:
      case SUNDAY:
        System.out.println("It's the weekend! Relax.");
        break;
      default:
        System.out.println("Just another mid-week day.");
        break;
    }
  }
}

Output:

TGIF! Almost the weekend.

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Why is this better than integers?

If we had used integers (public static final int MONDAY = 1), our switch statement would look like this:

int today = 5;
switch (today) {
  case 1: ...
  case 5: ...
}

This is known as using "Magic Numbers". It is very hard to read because the number 5 has no inherent meaning to a developer reading the code. The compiler also can't stop you from doing case 99:, which is an invalid day.

By using an Enum in the switch statement:

1. The code documents itself (you read case FRIDAY:).
2. The compiler guarantees that you can only switch on valid Day constants.