Map根据value值进行倒序排列

public List<Map.Entry<Integer,BigDecimal>> sortByMapValue(HashMap<Integer, BigDecimal> map){
        ArrayList<Map.Entry<Integer, BigDecimal>> list = new ArrayList<>(map.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<Integer, BigDecimal>>() {
            @Override
            public int compare(Map.Entry<Integer, BigDecimal> o1, Map.Entry<Integer, BigDecimal> o2) {
                if (o1.getValue() == null || o2.getValue() == null){
                    return -1;
                }
                return o2.getValue().compareTo(o1.getValue());
            }
        });
        return list;
    }

参考文章；https://www.cnblogs.com/liujinhong/p/6113183.html