Java Stream处理2个List集合取交集、并集、差集

package com.example.demo;

import java.util.ArrayList;
import java.util.List;

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

/**

• @author xuezj

• @date 2022/8/10 16:38
  */
  public class Test {

  public static void main(String[] args) {

   List<String> list1 = new ArrayList<>();
   list1.add("1");
   list1.add("2");
   list1.add("3");
   list1.add("5");
   list1.add("6");
  
   List<String> list2 = new ArrayList<>();
   list2.add("2");
   list2.add("3");
   list2.add("7");
   list2.add("8");
  
   System.out.print("List1-->");
   list1.parallelStream().forEachOrdered(System.out::print);
   System.out.println();
  
   System.out.print("List2-->");
   list2.parallelStream().forEachOrdered(System.out::print);
   System.out.println();
  
   // 交集
   List<String> intersection = list1.stream().filter(item -> list2.contains(item)).collect(toList());
   System.out.print("交集-->");
   intersection.parallelStream().forEach(System.out::print);
   System.out.println();
  
   // 差集 (list1 - list2)
   List<String> reduce1 = list1.stream().filter(item -> !list2.contains(item)).collect(toList());
   System.out.print("差集(list1 - list2)-->");
   reduce1.parallelStream().forEach(System.out::print);
   System.out.println();
  
   // 差集 (list2 - list1)
   List<String> reduce2 = list2.stream().filter(item -> !list1.contains(item)).collect(toList());
   System.out.print("差集(list2 - list1)-->");
   reduce2.parallelStream().forEach(System.out::print);
   System.out.println();
  
   // 并集
   List<String> listAll = list1.parallelStream().collect(toList());
   List<String> listAll2 = list2.parallelStream().collect(toList());
   listAll.addAll(listAll2);
   System.out.print("并集-->");
   listAll.parallelStream().forEachOrdered(System.out::print);
   System.out.println();
  
   // 去重并集
   List<String> listAllDistinct = listAll.stream().distinct().collect(toList());
   System.out.print("并集去重-->");
   listAllDistinct.parallelStream().forEachOrdered(System.out::print);
  

  }
  }
  输出结果：
  List1-->12356
  List2-->2378
  交集-->32
  差集(list1 - list2)-->561
  差集(list2 - list1)-->87
  并集-->123562378
  并集去重-->1235678