集合比较

  List<Map.Entry<Integer, Integer>> infoIds = new ArrayList<Map.Entry<Integer, Integer>>(
                map.entrySet());
       
        Collections.sort(infoIds, new Comparator<Map.Entry<Integer, Integer>>()
        {
            public int compare(Map.Entry<Integer, Integer> o1,
                    Map.Entry<Integer, Integer> o2)
            {
                return (o1.getKey() - o2.getKey()); //升序
            }
        });