What is the use of EnumSet in Java?

What is the use of EnumSet 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 EnumSet must come from a single enumeration type that is specified when the set is created either explicitly or implicitly.

What is an EnumSet?

An EnumSet is a specialized Set collection to work with enum classes. It implements the Set interface and extends from AbstractSet: Even though AbstractSet and AbstractCollection provide implementations for almost all the methods of the Set and Collection interfaces, EnumSet overrides most of them.

How and when would you use the enum collection?

Enums are used when we know all possible values at compile time, such as choices on a menu, rounding modes, command line flags, etc. It is not necessary that the set of constants in an enum type stay fixed for all time. In Java (from 1.5), enums are represented using enum data type.

What is EnumMap and EnumSet?

EnumMap is a specialized implementation of the Map interface for the enumeration types. EnumSet is a specialized implementation of the Set interface for the enumeration types. EnumMap is internally represented as an array. EnumSet is internally represented as a BitVector.

Is EnumSet immutable?

3 Answers. Returns an immutable set instance containing the given enum elements. Internally, the returned set will be backed by an EnumSet. The iteration order of the returned set follows the enum’s iteration order, not the order in which the elements appear in the given collection.

Does EnumSet allow null?

Null elements are not permitted. Attempts to insert a null element will throw NullPointerException . Attempts to test for the presence of a null element or to remove one will, however, function properly. Like most collection implementations, EnumSet is not synchronized.

Can a final map be modified?

Final means you cannot change the value of the variable.

How do you create an EnumMap in Java?

Java EnumMap Example

1. import java.util.*;
2. public class EnumMapExample {
3. // create an enum.
4. public enum Days {
5. Monday, Tuesday, Wednesday, Thursday.
6. };
7. public static void main(String[] args) {
8. //create and populate enum map.

What do you need to know about EnumSet in Java?

EnumSet is one of the specialized implementation of Set interface for use with the enumeration type. 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.

How to create a subset of an enum?

Another way to create a subset of an enum is by using the range () method: In the example above, the EnumSet contains all the elements from Yellow to Blue.

Is the EnumSet class synchronized in Java collections?

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.

Which is faster EnumSet or HashSet 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 EnumSet must come from a single enumeration type that is specified when the set is created either explicitly or implicitly.