继承Comparable接口来实现排序

List<Map> maps=new ArrayList<>();
//对maps进行赋值
 Comparator comp = new Comparator() {
                        @Override
                        public int compare(Object o1, Object o2) {
                            Map<String, Object> mapO1 = (Map<String, Object>) o1;
                            Map<String, Object> mapO2 = (Map<String, Object>) o2;
                            Date date1 = new Date();
                            Date date2 = new Date();
                            try {
                                date1 = DateUtil.string2Date(mapO1.get("createDate").toString());
                                date2 = DateUtil.string2Date(mapO2.get("createDate").toString());
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                            if (date1.compareTo(date2) > 0) {
                                return 1;
                            } else {
                                return -1;
                            }
                        }
                    };
                    Collections.sort(maps, comp);