Lambda表达式获取差集、交集、并集

- 日理万妓 2024-02-05 12:05 54阅读 0赞

使用Lambda进行获取两个集合之间的差集、交集、并集

@Test
        public void doSome(){
            List<String> oldList = Arrays.asList("1", "2", "3", "4");
            List<String> newList = Arrays.asList("3", "4", "5", "6");
    
            getDiffSet(oldList, newList);
            getDiffSet(newList, oldList);
            getIntersection(oldList, newList);
            getUnion(oldList, newList);
        }
    
        //差集方法
        private void getDiffSet(List<String> oldList, List<String> newList) {
            List<String> collect = newList.stream().filter(str -> {
                return !oldList.contains(str);
            }).collect(toList());
            log.info("差集内容--{}", JSON.toJSONString(collect));
        }
    
        //交集方法
        private void getIntersection(List<String> oldList, List<String> newList) {
            List<String> collect = newList.stream().filter(str -> {
                return oldList.contains(str);
            }).collect(toList());
            log.info("交集内容--{}", JSON.toJSONString(collect));
        }
    
        //并集
        private void getUnion(List<String> oldList, List<String> newList) {
            //使用新的集合 不然会报错
            List<String> collectOld = oldList.parallelStream().collect(toList());
            List<String> collectNew = newList.parallelStream().collect(toList());
            //并集
            collectOld.addAll(collectNew);
            List<String> collect = collectOld.stream().distinct().collect(toList());
            log.info("并集内容--{}", JSON.toJSONString(collect));
        }

结果集：

差集内容--["5","6"]
    差集内容--["1","2"]
    交集内容--["3","4"]
    并集内容--["1","2","3","4","5","6"]