Set operations: union, intersection, difference

 
import java.util.LinkedHashSet;
import java.util.Set;

public class SetOps {

  /**
   * @return the union of s1 and s2. (The union of two sets is the set
   *         containing all of the elements contained in either set.)
   */
  public static <T> Set<T> union(Set<T> s1, Set<T> s2) {
    Set<T> union = new LinkedHashSet<T>(s1);
    union.addAll(s2);
    return union;
  }

  /**
   * @return the intersection of s1 and s2. (The intersection of two sets is
   *         the set containing only the elements common to both sets.)
   */
  public static <T> Set<T> intersection(Set<T> s1, Set<T> s2) {
    Set<T> intersection = new LinkedHashSet<T>(s1);
    intersection.retainAll(s2);
    return intersection;
  }

  /**
   * @return the (asymmetric) set difference of s1 and s2. (For example, the
   *         set difference of s1 minus s2 is the set containing all of the
   *         elements found in s1 but not in s2.)
   */
  public static <T> Set<T> difference(Set<T> s1, Set<T> s2) {
    Set<T> difference = new LinkedHashSet<T>(s1);
    difference.removeAll(s2);
    return difference;
  }
}