What does EnumSet really mean?

Question

I have the following example:

import java.util.EnumSet;
import java.util.Iterator;

public class SizeSet {

    public static void main(String[] args) {
             


        

Answer 1

An EnumSet is a specialized Set collection to work with enum classes. It implements the Set interface and extends from AbstractSet:

When you plan to use an EnumSet youhave to take into consideration some points:

1. It can contain only enum values and all the values have to belong to the same enum
2. It doesn’t allow to add null values, throwing a NullPointerException in an attempt to do so
3. It’s not thread-safe, so we need to synchronize it externally if required
4. The elements are stored following the order in which they are declared in the enum
5. It uses a fail-safe iterator that works on a copy, so it won’t throw a ConcurrentModificationException if the collection is modified when iterating over it

Now, the EnumSet largeSize part is a variable declaration so yes, it's of type EnumSet. Please notice that you can add the type of elements in the collection for better type safety: EnumSet

Check out this article to learn more about EnumSet.