Why to use Enum in Java?

In this article, you will be acknowledged about the Enum in java, its uses and mainly its purpose. Enum has various functionalities. Each of them will be discussed.

Enum

In a computer language, enumerations are used to express a set of named constants. For instance, the four suits in a set of playing cards could be represented by the enumerators Clubs, Diamonds, Hearts, and Spade, which are members of the enumerated type Suit. The natural enumerated kinds are another example (like  planets, days in a week, colors, directions, etc.).

Enums are employed when all potential values are known at the time of compilation, as in the case of menu options, rounding methods, command-line flags, etc. The collection of constants through an enum type need not remain consistent throughout time.

A class type in Java is an enumeration. Although we don't need to use new to create an instance of an enum, it can still perform the same functions as other classes. Enumeration in Java is a very effective tool because of this aspect. You may give them constructors, add instance methods and variables and sometimes even implement interfaces, just like you can with classes.

Keep in mind that enumerations cannot inherit from other classes or be expanded, unlike classes (i.e become superclass).

Enums can represented using the enum data type in Java (as of version 1.5). Enums in Java are more capable than those in C/C++. Variables, methods, or rather constructors can all be added to it in Java. Enum's primary goal is to allow us to create custom data types (Enumerated Data Types)

Declaration

Enum declarations can be made either inside or outside of classes, but not within methods.

Let us look at an example program

File name: Choice.java

// A straightforward example of an enum that is stated outside of any class
//(Note that enum is the term here instead of class.)
enum Color {
RED,
GREEN,
BLUE;
}


public class Choice {
public static void main(String[] args)
{
Color c1 = Color.GREEN;
System.out.println(c1);
}
}

Output

GREEN

Key Functionalities of Enum

• Internally, each enum is implemented using a Class.
• An object of the type enum is represented by each enum constant.
• Switch statements accept arguments of the enum type.
• An enum constant is implicitly static final and public. We may retrieve it by employing the enum Name because it is static. We are unable to generate child enums since it is final.
• Inside the enum, we can define the main() method. As a result, we can call enum right from a Command Prompt.

The Purpose

• When an enum is created, the Java compiler dynamically adds the values() function. All of the enum's values are returned in an array via the values() method.
• When it builds an enum, the Java compiler automatically includes the function valueOf()  function. The value of the specified constant enum is returned by the function valueOf() method.
• When it builds an enum, the Java compiler automatically inserts the ordinal() function. The position of the enum value is returned by the ordinal() method.
• Enum enhances type safety during compile-time verification to prevent mistakes at run-time.
• Enum may be utilized in switches with ease.
• Enum can also be handled with ease.
• Fields, constructors, or even methods can be found in enum.
• Enum may implement numerous interfaces, but it effectively extends the Enum class, hence it cannot extend any other class.
• Enums restrict you to the necessary set of inputs, whereas constant strings still let you to use other Strings outside of your logic.
• This makes it easier to enter data without making a mistake or entering something inappropriate, and it also makes the programme easier to understand.
• In addition to not allowing you to submit a value that is erroneous, enums have one more characteristic that, while it may seem little, in my opinion it is quite significant. There is no reliable way to predict the potential values of a string constant, whereas modern IDEs can automatically suggest values for enums (The latter is accomplished by Intellij IDEA, including for JDK class and widely-used libraries). This is especially useful if you're learning about a new API.
• Since they generate instances of their components, enums impose overhead. You'll observe that the Android platform has the fewest possible enums and that practically all of its constants were final static int.