Java Code:
import java.util.*;

/** Show the union and instersection of two sets. */
public class SetStuff {
  public static void main(String[] args) {

    // Create two sets.
    Set s1 = new HashSet();
    s1.add("Ian Darwin");
    s1.add("Bill Dooley");
    s1.add("Jesse James");

    Set s2 = new HashSet();
    s2.add("Ian Darwin");
    s2.add("Doolin' Dalton");

    Set union = new TreeSet(s1);
    union.addAll(s2);    // now contains the union

    print("union", union);

    Set intersect = new TreeSet(s1);
    intersect.retainAll(s2);

    print("intersection", intersect);

  }

  protected static void print(String label, Collection c) {

    System.out.println("--------------" + label + "--------------");

    Iterator it = c.iterator();
    while (it.hasNext()) {
      System.out.println(it.next());
    }
  }
}