How to use HashSet in java?

This is a simple program that use HashSet:

import java.util.*;
public class HashSetClass {
public static void main(String[] args){
HashSet hs = new HashSet();
for(int i=0; i<10;i++)
hs.add(i);

Iterator iteration = hs.iterator();
for (Iterator iterator = hs.iterator(); iterator.hasNext();) {
Object object = (Object) iterator.next();
System.out.println(object);
}
}
}