Java Enum Constructors Explained with Practical Example

Java Enum Constructors Explained

Learn how to define and use constructors within Java enums through a clear, step‑by‑step example.

Before exploring enum constructors, review the basics of Java enum types.

In Java, an enum class can contain a constructor just like any other class. The constructor is typically private—accessible only inside the enum itself—or package‑private, which limits access to the same package.

Example: Enum Constructor in Action

enum Size {
   SMALL("The size is small."),
   MEDIUM("The size is medium."),
   LARGE("The size is large."),
   EXTRALARGE("The size is extra large.");

   private final String pizzaSize;

   private Size(String pizzaSize) {
      this.pizzaSize = pizzaSize;
   }

   public String getSize() {
      return pizzaSize;
   }
}

class Main {
   public static void main(String[] args) {
      Size size = Size.SMALL;
      System.out.println(size.getSize());
   }
}

Output

The size is small.

In this illustration, the Size enum defines a private constructor that accepts a String argument. The enum constants—SMALL, MEDIUM, LARGE, and EXTRALARGE—invoke this constructor, passing a descriptive message. The pizzaSize field stores the value, and the public getSize() method exposes it.

Because the constructor is private, it cannot be called from outside the enum. Instead, each constant automatically triggers the constructor during class initialization. In the Main class, selecting Size.SMALL creates an instance whose getSize() method returns the assigned string.