java根据list中的对象某个属性排序

public class Test {    public static void main(String[] args) throws Exception {        CityModel city1 = new CityModel();        city1.setCity_code(1);

CityModel city2 = new CityModel();        city2.setCity_code(1);

CityModel city3 = new CityModel();        city3.setCity_code(1);

CityModel city4 = new CityModel();        city4.setCity_code(1);

CityModel city5 = new CityModel();        city5.setCity_code(1);

ArrayList<CityModel> list = new ArrayList<>();        list.add(city1);        list.add(city2);        list.add(city3);        list.add(city4);        list.add(city5);

Collections.sort(list, new Comparator<CityModel>(){            public int compare(CityModel o1, CityModel o2) {                //按照CityModel的city_code字段进行降序排列

                if(o1.getCity_code() < o2.getCity_code()){                    return 1;                }                if(o1.getCity_code() == o2.getCity_code()){                    return 0;                }                return -1;            }        });

System.out.println(list);    }}