java 集合交并补

通过使用泛型方法和Set来表达数学中的表达式：集合的交并补，在以下三个方法中都将第一个参数Set复制了一份，并未直接修改参数中Set。

package Set;import java.util.HashSet;import java.util.Set;public class Sets {public  static <T> Set<T> intersection(Set<T> s1, Set<T> s2) {Set<T> result = new HashSet<T>(s1);result.retainAll(s2);return result;}public  static <T> Set<T> union(Set<T> s1, Set<T> s2) {Set<T> result = new HashSet<T>(s1);result.addAll(s2);return result;}//Subtract subset from supersetpublic  static <T> Set<T> difference (Set<T> superset, Set<T> subset) {Set<T> result = new HashSet<T>(superset);result.addAll(subset);return result;}//Reflexive --everything not in their intersectionpublic static <T> Set<T> complement(Set<T>s1,Set<T> s2){return difference(union(s1,s2),intersection(s1,s2));}}