ArrayList和HashMap的性能

增,找,删,性能对比

public class Test {
    public static void main(String[] args) {

        long startTime = System.currentTimeMillis();
        List<Cat> list = new ArrayList<>();
        List<Cat> remove = new ArrayList<>();
        for (int i = 0; i < 1000000; i++) {
            list.add(new Cat("huahua" + i));
        }
        long endTime = System.currentTimeMillis();
        System.out.println("list add 耗时" + (endTime - startTime) + " 毫秒");
        System.out.println("----------------------");


        // 打乱heros中元素的顺序
        Collections.shuffle(list);
        startTime = System.currentTimeMillis();
        for (Cat cat : list) {
            if (cat.name.equals("huahua" + 150000)) {
                endTime = System.currentTimeMillis();
                System.out.println("list find 耗时" + (endTime - startTime) + " 毫秒");
            }
        }

        System.out.println("----------------------");

        startTime = System.currentTimeMillis();
        for (Cat cat : list) {
            if (cat.name.equals("huahua" + 150000)) {
                remove.remove(cat);
            }
        }
        list.remove(remove);
        endTime = System.currentTimeMillis();
        System.out.println("list remove 耗时" + (endTime - startTime) + " 毫秒");
        System.out.println("----------------------");

        startTime = System.currentTimeMillis();
        HashMap<String, Cat> heroMap = new HashMap<String, Cat>();
        for (int j = 0; j < 1000000; j++) {
            Cat cat = new Cat("huahua" + j);
            heroMap.put(cat.name, cat);
        }
        endTime = System.currentTimeMillis();
        System.out.println("map put 耗时" + (endTime - startTime) + " 毫秒");
        System.out.println("----------------------");


        startTime = System.currentTimeMillis();
        heroMap.get("huahua" + 150000);
        endTime = System.currentTimeMillis();
        System.out.println("map find 耗时" + (endTime - startTime) + " 毫秒");
        System.out.println("----------------------");

        startTime = System.currentTimeMillis();
        heroMap.remove("huahua" + 150000);
        endTime = System.currentTimeMillis();
        System.out.println("map move 耗时" + (endTime - startTime) + " 毫秒");
    }

    static class Cat {
        private String name;

        public Cat(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

结果:

list add 耗时372 毫秒
----------------------
list find 耗时89 毫秒
----------------------
list remove 耗时268 毫秒
----------------------
map put 耗时767 毫秒
----------------------
map find 耗时0 毫秒
----------------------
map move 耗时0 毫秒

结论: List 在存数据上比Map快很多,找数据和删除数据比Map慢很多.