JAVA里List集合中的对象根据对象的某个属性值降序或者升序排序

public static void main(String[] args) throws ParseException {

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        List list = new ArrayList<>();
        person person1 = new person(sdf.parse("2018-01-15 17:41:38"),1);
        list.add(new person(sdf.parse("2018-01-15 17:41:38"),1));
        list.add(new person(sdf.parse("2018-02-15 17:41:38"),2));
        list.add(new person(sdf.parse("2018-04-15 17:41:38"),3));
        list.add(new person(sdf.parse("2018-03-15 17:41:38"),4));
        //根据person对象中的time字段进行降序排序
        list.sort(Comparator.comparing(person::getTime).reversed());
        //根据person对象中的time字段进行升序排序
        list.sort(Comparator.comparing(person::getTime));
        System.out.println(list);
    }


class person{

    public Date time;
    public int id;

    public person(Date time, int id) {
        this.time = time;
        this.id = id;
    }

    public Date getTime() {
        return time;
    }

    public void setTime(Date time) {
        this.time = time;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "person{" +
                "time=" + time +
                ", id=" + id +
                '}';
    }