public class Sets {
  //并
 
  public static <T> Set<T> union(Set<T> a, Set<T> b) {
    Set<T> result = new HashSet<T>(a);
    result.addAll(b);
    return result;
  }//交
  public static <T> Set<T> intersection(Set<T> a, Set<T> b) {
    Set<T> result = new HashSet<T>(a);
    result.retainAll(b);
    return result;
  }
  // 差
  public static <T> Set<T>
  difference(Set<T> superset, Set<T> subset) {
    Set<T> result = new HashSet<T>(superset);
    result.removeAll(subset);
    return result;
  }
  // 两个并集-两个交集
  public static <T> Set<T> complement(Set<T> a, Set<T> b) {
    return difference(union(a, b), intersection(a, b));
  }
} ///:~

//列举常量
package generics.watercolors;
public enum Alpha {a,b,c,d,e,f}

//使用上面方法的类
package generics;

import generics.watercolors.*;
import java.util.*;
import static net.mindview.util.Print.*;
import static net.mindview.util.Sets.*;
import static generics.watercolors.Alpha.*;

public class WatercolorSets {
public static void main(String[] args) {
Set<Alpha> set1 = EnumSet.range(a,e);
Set<Alpha> set2 = EnumSet.range(c,f);
print("set1: " + set1);
print("set2: " + set2);
print("并: " + union(set1, set2));
Set<Alpha> subset = intersection(set1, set2);
print("交: " + subset);
print("差1: " + difference(set1, subset));
print("差2: " + difference(set2, subset));
print("并-交: " + complement(set1, set2));
}
}

//类的连接（实例）变量
  static Set<String> object = methodSet(Object.class);

//类的静态块
  static { object.add("clone"); }

//两个集合类的方法差集
  static void difference(Class<?> superset, Class<?> subset) {
 System.out.print(superset.getSimpleName() +" extends " + subset.getSimpleName() + ", adds: ");
    Set<String> comp = Sets.difference(methodSet(superset), methodSet(subset));
    comp.removeAll(object); // Don't show 'Object' methods
    System.out.println(comp);
    interfaces(superset);
  }
  public static void main(String[] args) {
    System.out.println("Collection: "+methodSet(Collection.class));
    interfaces(Collection.class);
    difference(Set.class, Collection.class);
    difference(HashSet.class, Set.class);
    difference(LinkedHashSet.class, HashSet.class);
    difference(TreeSet.class, Set.class);
    difference(List.class, Collection.class);
    difference(ArrayList.class, List.class);
    difference(LinkedList.class, List.class);
    difference(Queue.class, Collection.class);
    difference(PriorityQueue.class, Queue.class);
    System.out.println("Map: " + methodSet(Map.class));
    difference(HashMap.class, Map.class);
    difference(LinkedHashMap.class, HashMap.class);
    difference(SortedMap.class, Map.class);
    difference(TreeMap.class, Map.class);
  }
} ///:~