import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Stream;
public class Main {
public static void main(String[] args) {
Set<Integer> numberSet = new HashSet<Integer>() {{
add(1);
add(2);
add(3);
}};
Stream<Integer> collectionStream = numberSet.stream();
System.out.println(Arrays.toString(collectionStream.toArray()));
}
}