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<Integer> list1 = Lists.newArrayList();
List<Integer> list2 = Lists.newArrayList();
Set<Integer> set3 = Sets.newHashSet();
Set<Integer> 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。