list內部元素排序

自定義排序，降序排:

     Collections.sort(list, new Comparator<Record>() {
            @Override
            public int compare(Record o1, Record o2) {
                return o2.getInt("id").compareTo(o1.getInt("id"));
            }
        });

自定義排序 升序排

 Collections.sort(list, new Comparator<Record>() {
            @Override
            public int compare(Record o1, Record o2) {
                return o1.getInt("id").compareTo(o2.getInt("id"));
            }
        });

Collections工具類，升序排:

 List<Integer> list = new ArrayList<>();
 list.add(3);
 list.add(5);
 list.add(1);

Collections.sort(list);

Collections.reverse(list);

System.out.println(list);

java8新特性，升序排:  lamda 表達式

 List<Integer> list = new ArrayList<>();
 
 list.sort(Integer::compareTo);

 list.stream().sorted((a,b)->b.compareTo(a)).forEach(System.out::println);
 list.stream().sorted(Comparator.reverseOrder()).forEach(System.out::println);