JAVA 8を利用して個の工具類を建てて集合の交差を求めて、そして集めて、差は集めます

public class CollectionUtil {

    /**
     *     
     * @param collection
     * @return
     */
    public static boolean isEmpty(Collection> collection) {

        return (collection == null || collection.isEmpty());

    }

    /**
     *     
     * @param collection
     * @return
     */
    public static boolean isNotEmpty(Collection> collection) {

        return !isEmpty(collection);

    }

    /**
     *    
     * @param masterList      
     * @param slaveList      
     * @param 
     * @return
     */

    public static  List getIntersection(List masterList, List slaveList) {

        return masterList.stream().filter(slaveList::contains).collect(Collectors.toList());

    }


    /**
     *    
     * @param masterList      
     * @param slaveList      
     * @param 
     * @return
     */

    public static  List getUnionSet(List masterList, List slaveList) {

        List list = new ArrayList<>();

        list.addAll(masterList);

        list.addAll(slaveList);

        return list.stream().distinct().collect(Collectors.toList());

    }

    /**
     *    
     * @param masterList      
     * @param slaveList      
     * @param 
     * @return
     */

    public static  List getDifferenceSet(List masterList, List slaveList) {

        return masterList.stream().filter(t -> !slaveList.contains(t)).collect(Collectors.toList());

    }

    //    
    public static void main(String[] args) {
        List list1 = Arrays.asList(1, 2, 3);
        List list2 = Arrays.asList(3, 4, 5);
        System.out.println("=========   =========");
        List intersection = CollectionUtil.getIntersection(list1,list2);
        intersection.forEach(System.out::println);

        System.out.println("=========   =========");
        List unionSet = CollectionUtil.getUnionSet(list1,list2);
        unionSet.forEach(System.out::println);

        System.out.println("=========   =========");
        List differenceSet = CollectionUtil.getDifferenceSet(list1,list2);
        differenceSet.forEach(System.out::println);
    }
}

コンソール印刷結果
==============================Disconnected from the target VM,address:'127.0.0.1:61891',transport:'socket'1 2 3 4 5========交差を求める=======1
アパッチも使えますCollectionsパッケージのCollectionsUtilsのツールクラス

package org.apache.commons.collections