Java EnumSet

In this tutorial, we will learn about the Java EnumSet class and its various methods with the help of examples.

The EnumSet class of the Java collections framework provides a set implementation of elements of a single enum.

EnumSet class which is implemented in the collections framework is one of the specialized implementation of Set interface for use with the enumeration type. It is a high performance set implementation, much faster than HashSet. All of the elements in an enum set must come from a single enumeration type that is specified when the set is created either explicitly or implicitly. Lets see how to create a set object using this class.

Example:

// Java program to demonstrate the 
// creation of the set object 
// using the EnumSet class 
import java.util.*; 

enum Code { 
	CODE, 
	LEARN, 
	CONTRIBUTE, 
	QUIZ, 
	MCQ 
} 
; 

public class Codemistic { 

	public static void main(String[] args) 
	{ 
		// Creating a set 
		Set<Code> set1; 

		// Adding the elements 
		set1 = EnumSet.of(Code.QUIZ, 
						Code.CONTRIBUTE, 
						Code.LEARN, 
						Code.CODE); 

		System.out.println("Set 1: " + set1); 
	} 
} 

output:
Set 1: [CODE, LEARN, CONTRIBUTE, QUIZ]

Few important features of EnumSet are as follows

It extends AbstractSet and implements Set Interface in Java.
EnumSet class is a member of the Java Collections Framework & is not synchronized.
It’s a high performance set implementation, much faster than HashSet.
All of the elements in an enum set must come from a single enumeration type that is specified when the set is created either explicitly or implicitly.

Methods in Java Enum Set

Method	Description
static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType)	It is used to create an enum set containing all of the elements in the specified element type.
static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c)	It is used to create an enum set initialized from the specified collection.
static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType)	It is used to create an empty enum set with the specified element type.
static <E extends Enum<E>> EnumSet<E> of(E e)	It is used to create an enum set initially containing the specified element.
static <E extends Enum<E>> EnumSet<E> range(E from, E to)	It is used to create an enum set initially containing the specified elements.
EnumSet<E> clone()	It is used to return a copy of this set.