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Enumerations

Enumerations in Java are a special data type that represents a group of named constants, defined using the enum keyword since Java 5. Enums can have attributes and methods, are implicitly public, static, and final, and can be used in switch statements. They improve type safety, restrict input parameters, and are iterable, making them a powerful feature in Java programming.

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18 views8 pages

Enumerations

Enumerations in Java are a special data type that represents a group of named constants, defined using the enum keyword since Java 5. Enums can have attributes and methods, are implicitly public, static, and final, and can be used in switch statements. They improve type safety, restrict input parameters, and are iterable, making them a powerful feature in Java programming.

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Ytber Upr
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© © All Rights Reserved
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Enumerations in Java

Unit-2

Enum Type
By
UMESH PRASAD ROUT
Enumerations in Java
● Enumerations serve the purpose of representing a group of named
constants in a programming language.
● An enum type is a special data type that enables for a variable to be a
set of predefined constants.The variable must be equal to one of the
values that have been predefined for it.
● An enum in Java is a special class that represents a group of constants.
● The enum keyword is used to define enum data type (also known as
Enumerated Data Type)
● It is available since Java 5.
● Example
enum Direction { EAST,WEST,NORTH,SOUTH}
2
Enums Vs Classes
● An enum can be just like a class, have attributes and
methods. The only difference is that enum constants are
public, static and final.
● An enum cannot be used to create objects, and it cannot
extend other classes (but it can implement interfaces).

3
Properties of Java Enum
● Java enum constants are public, static and final implicitly.
● Enum can be traversed(using loop).
● Enum can have fields, constructors and methods.
● Enum can be easily used in switch.
● Enum may implement many interfaces but cannot extend
any class because it internally extends Enum class.

4
Some Examples Java Enum
enum Direction {EAST,WEST,NORTH,SOUTH}
enum Color {RED,GREEN,BLUE}
enum Day
{SUNDAY,MONDAY,TUESDAY,WEDNESDAY
,THURSDAY,FRIDAY,SATURDAY}
enum Season {WINTER, SPRING, SUMMER, FALL}
enum Level {LOW,MEDIUM,HIGH}

5
Java Enum Demo Program
class EnumDemo { BLUE
enum Color {
RED
RED,
GREEN
GREEN,
BLUE BLUE
}
public static void main(String[] args) {
Color x = Color.BLUE;
System.out.println(x);
for (Color s : Color.values()) //Traversing Enum
System.out.println(s);
}}
6
Enum in a Switch Statement
enum Level {
Medium level
LOW,
MEDIUM,
HIGH
}
public class EnumTest {
public static void main(String[] args) {
Level x = Level.MEDIUM;
switch(x) {
case LOW:
System.out.println("Low level");
break;
case MEDIUM:
System.out.println("Medium level");
break;
case HIGH:
System.out.println("High level");
break;
7
}}}
Advantages of Java Enum
● Enum improves type safety
● Restrict input parameter in method
● Enums are iterable
● Usable in switch case
● Enum constants can hold values specified at the creation
time

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