The EnumSet class in Java is designed specifically for working with enum types as a specialized implementation of the Set interface. It extends the AbstractSet class.
EnumSet class hierarchy
The diagram below illustrates the hierarchy of the EnumSet class.
EnumSet class declaration
Let's examine the declaration of the java.util.EnumSet class.
Example
public abstract class EnumSet<E extends Enum<E>> extends AbstractSet<E> implements Cloneable, Serializable
Methods of Java EnumSet class
| Method | Description | |||
|---|---|---|---|---|
| static | static <span> EnumSet</span> allOf(Class<code> elementType) | It is used to create an enum set containing all of the elements in the specified element type. | > EnumSetEnumSet allOf(ClassClass elementType) | It is used to create an enum set containing all of the elements in the specified element type. |
| static | static <span> EnumSet</span> copyOf(Collection<? extends E> c) | It is used to create an enum set initialized from the specified collection. | > EnumSetEnumSet copyOf(CollectionCollection<E> c) | It is used to create an enum set initialized from the specified collection. |
| static <span> EnumSet</span>> EnumSetEnumSet noneOf(ClassClass elementType) | It is used to create an empty enum set with the specified element type. | |||
| static <span> EnumSet</span>> EnumSet<span> EnumSet</span> of(E e) | It is used to create an enum set initially containing the specified element. | |||
| static <span> EnumSet</span>> EnumSetEnumSet 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. |
Java EnumSet Example
Example
import java.util.*;
enum days {
SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}
public class Main {
public static void main(String[] args) {
Set<days> set = EnumSet.of(days.TUESDAY, days.WEDNESDAY);
// Traversing elements
Iterator<days> iter = set.iterator();
while (iter.hasNext())
System.out.println(iter.next());
}
}
Output:
Output
TUESDAY
WEDNESDAY
Java EnumSet Example: allOf and noneOf
Example
import java.util.*;
enum days {
SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}
public class Main {
public static void main(String[] args) {
Set<days> set1 = EnumSet.allOf(days.class);
System.out.println("Week Days:"+set1);
Set<days> set2 = EnumSet.noneOf(days.class);
System.out.println("Week Days:"+set2);
}
}
Output:
Output
Week Days:[SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY]
Week Days:[]
