Collections.sort(myRankList,new Comparator<RankIndexRsp.RankListVo>(){
    @Override
    public int compare(RankIndexRsp.RankListVo arg0, RankIndexRsp.RankListVo arg1) {
        Integer a = Integer.valueOf(arg0.getRankNumber());
        Integer b = Integer.valueOf(arg1.getRankNumber());
        // 升序
        return a.compareTo(b);

    }
});