List findIntersection getUnion

List findIntersection & getUnion  求两个列表的交集和并集

package zwf;import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;/*** 列表工具类* * @author ZengWenFeng* @date 2025.04.22* @mobile 13805029595* @email 117791303@qq.com*/
public class ListUtil
{/*** 计算两个列表的交集** @param listA [1,2,3,4,5]* @param listB [ 2, 4,5,7,8]* @return listC [ 2, 4,5]*/public static List<Long> findIntersection(List<Long> listA, List<Long> listB){if (listA == null || listA.size() <= 0 || listB == null || listB.size() <= 0){return null;}List<Long> result = new ArrayList<Long>();for (Long element : listA){if (listB.contains(element)){result.add(element);}}return result;}/*** 计算两个列表的并集** @param listA [1,2,3,4,5]* @param listB [ 2, 4,5,7,8]* @return listC [1,2,3,4,5,7,8]*/public static List<Long> getUnion(List<Long> listA, List<Long> listB){if (listA == null && listB == null){return new ArrayList<Long>();}if (listA == null){return new ArrayList<Long>(new LinkedHashSet<Long>(listB));}if (listB == null){return new ArrayList<Long>(new LinkedHashSet<Long>(listA));}LinkedHashSet<Long> unionSet = new LinkedHashSet<>(listA.size() + listB.size());if (listA.size() > 0){unionSet.addAll(listA);}if (listB.size() > 0){unionSet.addAll(listB);}return new ArrayList<Long>(unionSet);}public static void main(String[] args){// 初始化列表 A 和 BList<Long> listA = new ArrayList<>();listA.add(1L);listA.add(2L);listA.add(3L);listA.add(4L);listA.add(5L);List<Long> listB = new ArrayList<>();listB.add(2L);listB.add(4L);listB.add(5L);listB.add(7L);// 计算交集List<Long> intersection = findIntersection(listA, listB);// 输出交集System.out.println("交集列表: " + intersection);// 计算并集List<Long> union = getUnion(listA, listB);// 输出并集System.out.println("并集列表: " + union);}
}