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

As for any variable, its type is found in its declaration:

EnumSet largeSize

So yes, largeSize (which should be named largeSizes since it's a collection) is of type EnumSet. It should also be generified, and thus be declared as

EnumSet largeSizes

What it means, is that largeSizes is of type EnumSet. An EnumSet is a Set which contains enum instance of a specific enum type, in a more efficient way than other Set implementations (like HashSet, TreeSet, etc.). To know what an EnumSet is, read its API.