JAVA 中集合取交集

日常工作 经常需要取两个数据集的交集。对常用的List 和Set集合做了一个测试

 public static void main(String[] args) {
        List list1 = Lists.newArrayList();
        List list2 = Lists.newArrayList();
        Set set3 = Sets.newHashSet();
        Set set4 = Sets.newHashSet();

        for (int i = 0; i < 100000; i++) {
            list1.add(i);
            set3.add(i);
            list2.add(i);
            set4.add(i);
        }

        System.out.println("list1 size " + list1.size());
        System.out.println("list2 size " + list2.size());
        System.out.println("set3 size " + set3.size());
        System.out.println("set4 size " + set4.size());
        StopWatch stopWatch =new StopWatch("交集测试");
        stopWatch.start("list交集测试");
        list2.parallelStream().filter(data -> list1.contains(data)).collect(Collectors.toList());
        stopWatch.stop();
        stopWatch.start("set交集测试");
        set4.parallelStream().filter(data -> set3.contains(data)).collect(Collectors.toSet());
        stopWatch.stop();

        StopWatch.TaskInfo[] taskInfo = stopWatch.getTaskInfo();

        Arrays.stream(taskInfo).forEach(taskInfo1 -> {
            System.out.println(taskInfo1.getTaskName()+"---"+taskInfo1.getTimeMillis()+"毫秒");

        });

    }

测试结果如下：数据量都是10万的情况下。set的性能是 164.6倍多。