What are enums and why are they useful?

java

enums

object-oriented

design-patterns

byNikita Barsukov·Aug 20, 2024

Enums in Java are typesafe collections of constants—they enable your code to be self-explanatory and error-resistant by switching out numeric or string literals for well-named values.

Example:

// Just like Skittles, taste the rainbow 🌈
public enum Color {
    RED, // like a 🌶️ 
    GREEN, // like a 🌳
    BLUE // like the 🌊
}

public class Palette {
    Color color;
    
    // No monochromatic life here, we need color!
    public Palette(Color color) {
        this.color = color;
    }
    
    // Time to mix things up a bit, like at a party 🥳
    public void mix() {
        if (color == Color.RED) {
            System.out.println("Warm color");
        } else if (color == Color.BLUE) {
            System.out.println("Cool color");
        } else {
            System.out.println("Neutral color");
        }
    }
    
    public static void main(String[] args) {
        Palette warmPalette = new Palette(Color.RED);
        warmPalette.mix(); 
        // Output: Warm color. Just like a cozy fireplace on a winter night. ☃️
    }
}

By adopting the strategy pattern and interfaces, enums support polymorphism, increasing their organizing power.

Type safety and clarity from enums

Enums provide compile-time checking, ensuring that only predefined, valid values are used, thereby making your code more resilient and less prone to errors from invalid constants.

Enums in action and polymorphism

The practice of using multiple methods, each incorporating different flags, gives your program's logic more modularity and clearness. Enums, being an Object-Oriented Programming (OOP) construct, can encapsulate methods and attributes just like classes.

Reducing complexity through Enums

By using enums, multiple flag arguments are replaced by a single enum argument. The result is neater method signatures and more expressive method call statements.

Enums and their design patterns

From a strategic standpoint, enums can be employed in strategy and singleton design patterns, offering both a thread-safe instance creation method and a behavior encapsulation mechanism.

Enum classes: OOP with a twist

Enums in Java are essentially classes, thus they can encapsulate complex structures. Enums can implement interfaces, possess fields, methods, and put forward their distinctive constructor. This opens up endless possibilities, from a simple data carrier to a finely tuned state machine.

Auto-implemented methods

Enums get methods like equals(), hashCode(), and toString() auto-implemented, making them great for collections and display needs. Their innate implementation of Serializable and Comparable aligns them with core Java specifications.

Enums: simplifying complexity

Enums provide an excellent way to conceal complex logic, thus promoting the encapsulation principle of Object-Oriented Programming (OOP). Instead of burdening users with a multitude of tiny variables and complex logic, you can present a set of well-defined options through enums.

Why enums are so cool!

Enums provide support for templated methods and can stand in for command-pattern receivers, offering highly flexible and reusable components of code. They allow static methods for specific utility usages, and static imports can create a DSL-like syntax for enhanced readability.

explain-codes / Java / What are enums and why are they useful?

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