Find Minimum element of HashSet in Java

/*from  w  ww  .  j a va  2 s  . c o  m*/
import java.util.Collections;
import java.util.HashSet;

public class Main {
  public static void main(String[] args) {
    HashSet<Long> hashSet = new HashSet<Long>();

    hashSet.add(new Long("9"));
    hashSet.add(new Long("4"));
    hashSet.add(new Long("2"));
    hashSet.add(new Long("2"));
    hashSet.add(new Long("3"));

    Object obj = Collections.min(hashSet);
    System.out.println("Minimum Element of Java HashSet is : " + obj);
  }
}