java - 如何从通过读取java中的CSV文件返回的矩阵中检索特定行

Question

我想检索二维数组的一些行。

示例:我有名为“data.csv”的文件，其中包含

age   sex  zipcode   classtype

21     m     23423   1

12     f     23133   2

23     m     32323   2

23     f     23211   1

下面提到的代码将给出如下输出:

{age=[21,12,23,23],sex=[m,f,m,f],zipcode=[23423,23133,32323,23211],classtype=[1,2,2,1]}

现在我想检索具有类类型 1 的行并将这些值存储在新的二维数组中。

像partition1={{21,m,23423,1},{23,f,23211,1}}

    public class CsvParser {
        public static void main(String[] args) {
            try {
                FileReader fr = new FileReader((args.length > 0) ? args[0] : "data.csv");
                Map<String, List<String>> values = parseCsv(fr, " ", true);
                System.out.println(values);
                List<List<String>> partition1 = new ArrayList<>(25);
                List<String> classTypes = values.get("classtype");
                for (int row = 0; row < classTypes.size(); row++) {
                     String classType = classTypes.get(row);
                     if ("1".equals(classType)) {
                     List<String> data = new ArrayList<>(25);
                     data.add(values.get("age").get(row));
                     data.add(values.get("sex").get(row));
                     data.add(values.get("zipcode").get(row));
                     data.add(values.get("classtype").get(row));
                     partition1.add(data);
                  }
           }

                 System.out.println(partition1);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    public static Map<String, List<String>> parseCsv(Reader reader, String separator, boolean hasHeader) throws IOException {
        Map<String, List<String>> values = new LinkedHashMap<String, List<String>>();
        List<String> columnNames = new LinkedList<String>();
        BufferedReader br = null;
        br = new BufferedReader(reader);
        String line;
        int numLines = 0;
        while ((line = br.readLine()) != null) {
            if (StringUtils.isNotBlank(line)) {
                if (!line.startsWith("#")) {
                    String[] tokens = line.split(separator);
                    if (tokens != null) {
                        for (int i = 0; i < tokens.length; ++i) {
                            if (numLines == 0) {
                                columnNames.add(hasHeader ? tokens[i] : ("row_"+i));
                            } else {
                                List<String> column = values.get(columnNames.get(i));
                                if (column == null) {
                                    column = new LinkedList<String>();
                                }
                                column.add(tokens[i]);
                                values.put(columnNames.get(i), column);
                            }
                        }
                    }
                    ++numLines;
                }
            }
        }
        return values;
    }
}

Answer 1

             FileReader file1 = new FileReader(file);
                BufferedReader buffer = new BufferedReader(file1);
                String line = "";
                while ((line = buffer.readLine()) != null) {
                       StringBuilder sb = new StringBuilder();
                       String[] str = line.split(",");
                       if(str[0]!=null||str[1]!=null||str[2]!=null){
                       sb.append("'" + str[0] + "',");
                       sb.append("'" +str[1] + "',");
                       sb.append("'" +str[2] + "'");
                       }

CSV 文件必须基于逗号分隔，它应该可以工作