Unlock the Power of EnumSets in Java
Getting Started with EnumSets
Before diving into the world of EnumSets, make sure you have a solid understanding of Java Enums. EnumSets are a type of set implementation that stores elements of a single enum, and they implement the Set interface.
Creating an EnumSet
To create an EnumSet, you need to import the java.util.EnumSet package. Unlike other set implementations, EnumSets don’t have public constructors. Instead, you’ll use predefined methods to create an EnumSet. Here are four ways to do it:
Using allOf() Method
The allOf() method creates an EnumSet that contains all the values of the specified enum type. For example:
java
EnumSet<Size> sizes = EnumSet.allOf(Size.class);
Using noneOf() Method
The noneOf() method creates an empty EnumSet. For example:
java
EnumSet<Size> sizes = EnumSet.noneOf(Size.class);
Using range() Method
The range() method creates an EnumSet containing all the values of an enum between two specified values, including both values. For example:
java
EnumSet<Size> sizes = EnumSet.range(Size.SMALL, Size.LARGE);
Using of() Method
The of() method creates an EnumSet containing the specified elements. For example:
java
EnumSet<Size> sizes = EnumSet.of(Size.SMALL, Size.MEDIUM, Size.LARGE);
Working with EnumSets
Now that you’ve created an EnumSet, let’s explore some of its methods.
Inserting Elements
You can insert elements into an EnumSet using the add() or addAll() methods. For example:
java
EnumSet<Size> sizes1 = EnumSet.of(Size.SMALL, Size.MEDIUM);
EnumSet<Size> sizes2 = EnumSet.of(Size.LARGE);
sizes2.addAll(sizes1);
Accessing Elements
To access elements of an EnumSet, use the iterator() method. Don’t forget to import the java.util.Iterator package.
java
Iterator<Size> iterator = sizes.iterator();
while (iterator.hasNext()) {
Size size = iterator.next();
System.out.println(size);
}
Removing Elements
You can remove elements from an EnumSet using the remove() or removeAll() methods. For example:
java
EnumSet<Size> sizes = EnumSet.of(Size.SMALL, Size.MEDIUM, Size.LARGE);
sizes.remove(Size.MEDIUM);
Other Methods
The EnumSet class also implements Cloneable and Serializable interfaces, which allow you to make copies of instances and transmit objects over a network, respectively.
Why Choose EnumSets?
EnumSets provide an efficient way to store enum values compared to other set implementations like HashSet and TreeSet. Since an EnumSet only stores enum values of a specific enum, the JVM already knows all the possible values of the set. This means enum sets are internally implemented as a sequence of bits, making them more efficient.