Set operations: symmetric difference, is subset, is superset

 
import java.util.Set;
import java.util.TreeSet;

public class Main {
  public static <T> Set<T> union(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>(setA);
    tmp.addAll(setB);
    return tmp;
  }

  public static <T> Set<T> intersection(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>();
    for (T x : setA)
      if (setB.contains(x))
        tmp.add(x);
    return tmp;
  }

  public static <T> Set<T> difference(Set<T> setA, Set<T> setB) {
    Set<T> tmp = new TreeSet<T>(setA);
    tmp.removeAll(setB);
    return tmp;
  }

  public static <T> Set<T> symDifference(Set<T> setA, Set<T> setB) {
    Set<T> tmpA;
    Set<T> tmpB;

    tmpA = union(setA, setB);
    tmpB = intersection(setA, setB);
    return difference(tmpA, tmpB);
  }

  public static <T> boolean isSubset(Set<T> setA, Set<T> setB) {
    return setB.containsAll(setA);
  }

  public static <T> boolean isSuperset(Set<T> setA, Set<T> setB) {
    return setA.containsAll(setB);
  }

  public static void main(String args[]) {
    TreeSet<Character> set1 = new TreeSet<Character>();
    TreeSet<Character> set2 = new TreeSet<Character>();

    set1.add('A');
    set1.add('B');
    set1.add('C');
    set1.add('D');

    set2.add('C');
    set2.add('D');
    set2.add('E');
    set2.add('F');

    System.out.println("set1: " + set1);
    System.out.println("set2: " + set2);

    System.out.println("Union: " + union(set1, set2));
    System.out.println("Intersection: " + intersection(set1, set2));
    System.out.println("Difference (set1 - set2): " + difference(set1, set2));
    System.out.println("Symmetric Difference: " + symDifference(set1, set2));

    TreeSet<Character> set3 = new TreeSet<Character>(set1);

    set3.remove('D');
    System.out.println("set3: " + set3);

    System.out.println("Is set1 a subset of set2? " + isSubset(set1, set3));
    System.out.println("Is set1 a superset of set2? " + isSuperset(set1, set3));
    System.out.println("Is set3 a subset of set1? " + isSubset(set3, set1));
    System.out.println("Is set3 a superset of set1? " + isSuperset(set3, set1));

  }
}
  
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Collection Set:
  1. Convert set to an Array
  2. Convert Set into List
  3. Convert a set to a synchronized Set
  4. Is a particular value in(exist) Set
  5. Iterator a set
  6. Maximum element of Set
  7. Minimum element of a Set
  8. Remove all elements from a set
  9. Remove element from Set
  10. Remove one set from another set
  11. Remove all the elements from one set to another set
  12. Union(Add) all the elements from one set to another set
  13. Intersection of one set and another set
  14. Set operations: union, intersection, difference
  15. Set operations: symmetric difference, is subset, is superset
  16. Size of a Set