Hello Jetto Net followers!

Welcome to our Java Object-Oriented Programming (OOP) series. In our previous post, we learned how to make our Java projects more organized and manageable through packages. In this post, we will explore "enums" (enumerations), a special class type in Java. Enums are a powerful tool used to represent a set of constant values, and they make our code more readable, type-safe, and less prone to errors.

What is an Enum?

Enum is short for "enumeration" and means "numbering" in English. In Java, an enum is a special class type that represents a set of predefined constant values. Enums are used to restrict the values a variable can take and to express these values with meaningful names.

Defining an Enum

To define an enum in Java, we use the enum keyword. The enum name should start with an uppercase letter and generally be a plural name (e.g., Days, Months, Colors). Inside the enum, constant values are listed separated by commas.

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

In the example above, we defined an enum named Days. This enum has seven constant values representing the days of the week.

Using Enums

Enum constants are accessed using the enum name followed by a dot (.) operator and the constant name.

Days today = Days.MONDAY;
System.out.println(today); // Output: MONDAY

Enum constants can also be used in switch-case structures.

switch (today) { 
	case MONDAY: 
		System.out.println("The week starts!"); 
		break; 
	case FRIDAY:
		System.out.println("The weekend is approaching!"); 
		break; 
	// ... other cases 
}

Advantages of Enums

• Type Safety: Enums provide type safety by restricting the values a variable can take, thus preventing invalid value assignments.
• Readability: Enum constants are expressed with meaningful names, which makes the code more readable.
• Ease of Maintenance: Since enum constants are defined in one place, updating values only requires modifying the enum definition.

Features of Enums

• Enums are actually a type of class. Therefore, they can have constructors, methods, and even fields.
• Enum constants are static and final. This means their values cannot be changed and there is only one instance of each enum constant.
• Enums implement the Comparable and Serializable interfaces. Thus, they are comparable and serializable.

Conclusion

Enums are a powerful tool in Java for representing a set of constant values. By using enums, we can make our code more readable, type-safe, and less error-prone. In our next post, we will continue exploring other important concepts of OOP. Feel free to leave your questions or comments in the section below.

Happy Coding!