csv读取列数据（一列一列读取成一个集合）

 public static Map> readRainfallCSV(String pathFile,String fileName)  {
        Map> result= new HashMap<>();
        try {
            File file = new File(pathFile+File.separator+fileName);
            List lines = Files.readAllLines(file.toPath(),
                    StandardCharsets.UTF_8);
            List names = Arrays.asList(lines.get(0).split(","));
            //第一个null值
            //循环逐列读取
            List> lineList = new ArrayList<>();
            lines.stream().forEach(item->lineList.add(Arrays.asList(item.split(","))));
            lineList.remove(lineList.get(0));
            for(int i=1;i item.get(finalI)).collect(Collectors.toList()));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }