Java8两个List集合取交集、并集、差集、去重并集

深碍√TFBOYSˉ_ 2024-04-07 14:01 72阅读 0赞

import java.util.ArrayList;
    import java.util.List;
    
    import static java.util.stream.Collectors.toList;
    
    
    public class CollectionsTest {
        
        public static void main(String[] args) {
        
            List<String> list1 = new ArrayList<>();
            list1.add("1");
            list1.add("2");
            list1.add("3");
            list1.add("4");
            list1.add("5");
    
            List<String> list2 = new ArrayList<>();
            list2.add("2");
            list2.add("3");
            list2.add("6");
            list2.add("7");
    
            // 交集
            List<String> 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<String> 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<String> 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<String> listAll = list1.parallelStream().collect(toList());
            List<String> 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<String> listAllDistinct = listAll.stream().distinct().collect(toList());
            System.out.println("---得到去重并集 listAllDistinct---");
            listAllDistinct.parallelStream().forEachOrdered(System.out::println);
    
        }
    
    }