Java8两个集合(List)取交集、并集、差集、去重并集

import java.util.ArrayList;

import java.util.List;

import static java.util.stream.Collectors.toList;

/**

• @author billzhen
• @version 1.0.0 *
• @date 2024/6/17 14:44
  **/
  public class CollectionsTest {
  public static void main(String[] args) {
  List list1 = new ArrayList<>();
  list1.add("1");
  list1.add("2");
  list1.add("3");
  list1.add("4");
  list1.add("5");
  List list2 = new ArrayList<>();
  list2.add("2");
  list2.add("3");
  list2.add("6");
  list2.add("7");
  // 交集
  List intersection = list1.stream().filter(item -> list2.contains(item)).collect(toList());
  System.out.println("---交集 intersection---");
  intersection.parallelStream().forEach(System.out::println);
  // 差集 (list1 - list2)
  List reduce1 = list1.stream().filter(item -> !list2.contains(item)).collect(toList());
  System.out.println("---差集 reduce1 (list1 - list2)---");
  reduce1.parallelStream().forEach(System.out::println);
  // 差集 (list2 - list1)
  List reduce2 = list2.stream().filter(item -> !list1.contains(item)).collect(toList());
  System.out.println("---差集 reduce2 (list2 - list1)---");
  reduce2.parallelStream().forEach(System.out::println);
  // 并集
  List listAll = list1.parallelStream().collect(toList());
  List listAll2 = list2.parallelStream().collect(toList());
  listAll.addAll(listAll2);
  System.out.println("---并集 listAll---");
  listAll.parallelStream().forEachOrdered(System.out::println);
  // 去重并集
  List listAllDistinct = listAll.stream().distinct().collect(toList());
  System.out.println("---得到去重并集 listAllDistinct---");
  listAllDistinct.parallelStream().forEachOrdered(System.out::println);
  }
  }