对比java的List,Set,Map查询速度

@org.junit.jupiter.api.Test
    public void compareArrayListAndHashMapAndSet1(){
    
    
        Map<Long, Long> map = new HashMap<>();
        for (int i = 0; i < 1000_0000; i++) {
    
    
            map.put(i+1L, i+1L);
        }
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000_0000; i++) {
    
    
            boolean b = map.containsKey(i + 1L);
        }
        long end = System.currentTimeMillis();
        System.out.println("1000w元素 map耗时:" + (end-start));

        List<Long> list = new ArrayList<>();
        for (int i = 0; i < 10_0000; i++) {
    
    
            list.add(i+1L);
        }
        long start2 = System.currentTimeMillis();
        for (int i = 0; i < 10_0000; i++) {
    
    
            boolean b = list.contains(i + 1L);
        }
        long end2 = System.currentTimeMillis();
        System.out.println("10W元素 list耗时:" + (end2-start2));

        Set<Long> set = new HashSet<>();
        for (int i = 0; i < 1000_0000; i++) {
    
    
            set.add(i+1L);
        }
        long start3 = System.currentTimeMillis();
        for (int i = 0; i < 1000_0000; i++) {
    
    
            boolean b = set.contains(i + 1L);
        }
        long end3 = System.currentTimeMillis();
        System.out.println("1000w元素 set耗时:" + (end3-start3));

    }

结论:

map和set因为底层用的hash表,所以差距不大;
因为我只存一个Long类型的id,所以我选择了Set
1000w元素时的List速度太慢,再见了!
推荐key,value选择HashMap;

网上找了个图:

连接在这:(尊重原创)
https://blog.csdn.net/high2011/article/details/106742629