enum in Java (original) (raw)

Last Updated : 09 Oct, 2025

In Java, enumerations (enums) are a special type used to define a group of named constants.

Enums help in readability, maintainability, and type safety in programs by assigning meaningful names to integer values.
Mainly useful when we have a small set of possible values for an item like directions, days of week, etc.

Creating an Enum

**Syntax:

enum EnumName {

CONSTANT1, CONSTANT2, CONSTANT3;

}

Java `

enum TrafficLight { RED, GREEN, YELLOW; }

public class Test{

public static void main(String[] args){
    
    TrafficLight x = TrafficLight.RED;
    System.out.println(x);
}

}

Declaration of enum in Java

Enum declaration can be done outside a class or inside a class but not inside a method.

1. Declaration outside the class

As we have seen in the above example, enums can be declared outside a class and accessed directly

2. Declaration inside a class

Enums can also be declared inside a class but not inside a method.

Java `

public class Test { enum Color { RED, GREEN, BLUE; }

// Driver method
public static void main(String[] args) {
    Color c1 = Color.RED;
    System.out.println(c1);
}

}

Properties of Enum in Java

There are certain properties followed by Enum as mentioned below:

**Class Type: Internally implemented as a class.
**Enum Constants: Each constant is an object of the enum type.
**Switch Support: Can be used in switch statements.
**Implicit Modifiers: Constants are public static final.
**Inheritance: Enums cannot extend classes but can implement interfaces.

Enum in a Switch Statement

Enums can be used in switch statements to handle different cases based on the enum constants.

Java `

import java.io.*;

class GFG{

// Enum Declared
enum Color {
    RED,
    GREEN,
    BLUE,
    YELLOW;
}

public static void main(String[] args){
    
    Color var_1 = Color.YELLOW;

    // Switch case with Enum
    switch (var_1) {
    case RED:
        System.out.println("Red color");
        break;
    case GREEN:
        System.out.println("Green color");
        break;
    case BLUE:
        System.out.println("Blue color");
        break;
    default:
        System.out.println("Other color");
    }
}

}

Enum with Methods and Constructor

Enums can have constructors and methods, executed separately for each constant

Java `

enum Color{ RED, GREEN, BLUE;

private Color(){
    
    System.out.println("Constructor called for: " + this);
}

public void display(){
    
    System.out.println("Color is: " + this);
}

}

public class Test{

public static void main(String[] args){
    
    Color c1 = Color.RED;
    c1.display();
}

}

Output

Constructor called for: RED Constructor called for: GREEN Constructor called for: BLUE Color is: RED

Enum with Abstract Methods

Enums can declare abstract methods that each constant must implement.

Java `

enum Day{

MONDAY{
    
    public String getNumber(){
        return "1st day"; 
        
    }
},
FRIDAY{
    
    public String getNumber(){
        return "5th day"; 
        
    }
};

public abstract String getNumber();

}

public class EnumTest { public static void main(String[] args){

    System.out.println(Day.MONDAY.getNumber()); 
    System.out.println(Day.FRIDAY.getNumber());
}

}

Iterating Enums Using values()

Use EnumType.values() to loop through all enum constants.

Java `

enum Color{ RED, GREEN, BLUE;

}

public class Test{

public static void main(String[] args){
    
    for (Color c : Color.values()){
        
        System.out.println(c);
    }
}

}

Enum and EnumSet (Specific Range Iteration)

EnumSet.range() allows iteration over a specific range of enum constants.

Java `

import java.util.EnumSet;

public class EnumSetExample{

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

public static void main(String[] args){
    
    EnumSet<Day> workDays = EnumSet.range(Day.TUESDAY, Day.FRIDAY);
    for (Day d : workDays){
        
        System.out.println(d);
    }
}

}

Output

TUESDAY WEDNESDAY THURSDAY FRIDAY

Creating a Class with an Enum Member

We can combine enums with regular classes to organize your program logic. An enum can be a member variable in a class, and methods can perform actions based on the enum value.

Java `

/*package whatever //do not write package name here */

import java.io.*;

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

public class EnumTest { // Enum member variable Day day;

// constructor which takes enum value
public EnumTest(Day day) { this.day = day; }

// method to execute action as per enum value
public void tellItLikeItIs()
{
    switch (day) {
    case MONDAY:
        System.out.println("Mondays are tough");
        break;
    case TUESDAY:
        System.out.println("Tuesday are better");
        break;
    case WEDNESDAY:
        System.out.println("Wednesday are okay");
        break;
    case THURSDAY:
        System.out.println("Thursdays are hopeful");
        break;
    case FRIDAY:
        System.out.println("Fridays are exciting");
        break;
    case SATURDAY:
        System.out.println("Saturdays are relaxing");
        break;
    case SUNDAY:
        System.out.println("Sunday are for rest");
        break;
    default:
        System.out.println("Everyday are good");
        break;
    }
}

public static void main(String[] args)
{
    EnumTest firstDay = new EnumTest(Day.MONDAY);
    firstDay.tellItLikeItIs();

    EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
    thirdDay.tellItLikeItIs();

    EnumTest fifthDay = new EnumTest(Day.FRIDAY);
    fifthDay.tellItLikeItIs();

    EnumTest sixthDay = new EnumTest(Day.SATURDAY);
    sixthDay.tellItLikeItIs();

    EnumTest seventhDay = new EnumTest(Day.SUNDAY);
    seventhDay.tellItLikeItIs();
}

}

Output

Mondays are tough Wednesday are okay Fridays are exciting Saturdays are relaxing Sunday are for rest

**Explanation:

The EnumTest class in above code is created with member of type Day. It has constructor which takes Day enum as an argument and assigns it.
The class has method tellItLikeItIs(), which prints message based on value of day.
The main method includes objects of EnumTest using different Day enum values and calling tellItLikeItIs() method on each.

**NOTE: The new keyword is used because EnumTest is a regular class, not an enum, so we create instances and pass the enum value to its constructor.