package thinkinginjava.util;

import java.util.*;

public class Sets {

public static <T> Set<T> union(Set<T> a, Set<T> b) {

Set<T> result = new HashSet<T>(a);

result.addAll(b);

return result;

}

public static <T> Set<T> intersection(Set<T> a, Set<T> b) {

Set<T> result = new HashSet<T>(a);

result.retainAll(b);

return result;

}

// Subtract subset from superset:

public static <T> Set<T> difference(Set<T> superset, Set<T> subset) {

Set<T> result = new HashSet<T>(superset);

result.removeAll(subset);

return result;

}

// Reflexive--everything not in the intersection:

public static <T> Set<T> complement(Set<T> a, Set<T> b) {

return difference(union(a, b), intersection(a, b));

}

} // /:~