java根据list中的对象某个属性排序

1、 Collections.sort

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);

25         Collections.sort(list, new Comparator<CityModel>(){
26             public int compare(CityModel o1, CityModel o2) {
27                 //按照CityModel的city_code字段进行降序排列
28                 if(o1.getCity_code() < o2.getCity_code()){
29                     return 1;
30                 }
31                 if(o1.getCity_code() == o2.getCity_code()){
32                     return 0;
33                 }
34                 return -1;
35             }
36         });

        System.out.println(list);
    }
}