使用Java流將標題和行的csv文件轉換為hashmap數組

Question

我如何使用Java流將頭和行的csv文件轉換為hashmap數組？ 例如。

orderNo, totals, charges, taxes, payments
ord121,1500.00,30.00,25.00,Paid
ord8925,1700.00,130.00,75.00,Paid
ord7115,300.00,130.00,75.00,Paid

Hashmap的數組[0]的名稱應為orderNo，值應為ord121
Hashmap的Array [1]的名稱應為orderNo，值應為ord8925 ...等

嘗試過此方法，但停留在如何使行（0）內容作為哈希圖名稱

公共靜態無效readFileToMap（）{

    Pattern pattern = Pattern.compile(",");
    String csvFile = inputDirPreFix + "input/file2.tsv";
    try (BufferedReader in = new BufferedReader(new FileReader(csvFile));){

        Map<String,String> namefreq = in
                .lines()
                .skip(1)
                .map(lineData -> pattern.split(lineData))
                .collect(HashMap::new, (map, lineData) ->
                                map.put(lineData[0], lineData[1]),
                        Map::putAll);
        namefreq.forEach((k, v) -> System.out.println(k + " => " + v));
    }
    catch (Exception ex) {
        Logger.getLogger("FileProcessing").log(Level.SEVERE, null, ex);
    }
}

Answer 1

我認為您應該將每一行都轉換為Map<String, String> ，然后將所有地圖收集到List<Map<String, String>> ：

try (BufferedReader in = new BufferedReader(new FileReader(csvFile))) {

    List<Map<String,String>> namefreq = in.lines()
        .skip(1)
        .map(line -> pattern.split(line)) // or pattern::split
        .map(line -> {
            Map<String, String> map = new HashMap<>();
            map.put("NAME_OF_FIRST_COLUMN", line[0]);
            map.put("NAME_OF_SECOND_COLUMN", line[1]);
            // ... (etc)
            return map;
         })
        .collect(Collectors.toList());
}

---

編輯：最好不要收集到地圖列表，而最好創建自己的類，即Order ，其中具有orderNo ， totals等屬性，還有getter和setter以及接收整行的構造函數，或者也許每一個屬性。 然后，您可以收集到List<Order> 。

Answer 2

暫時沒有流管理...

public static void readFileToMap() {

    String csvFile = inputDirPreFix + "input/file2.tsv";
    String []  strArrHeaderFields =new String [20]  ;
    HashMap objDataHashMap ;
    HashMap <Integer,Object> objAggregateData = new HashMap(); ;

    String [] strArrValues = new String[20];

    try {
        List<String> fileLinesList = Files.readAllLines(Paths.get(csvFile));

        strArrHeaderFields =fileLinesList.get(0).split(",");
        //System.out.println( Arrays.toString(objHeaderFields)  );

        //skip header line and collect data lines in hashmap with Name as Header line values..
        // for every data line,
        for( int i=1; i< fileLinesList.size(); i ++) {
            objDataHashMap = new HashMap();
            //get values from each data line
            strArrValues =fileLinesList.get(i).split(",");

            for( int j=0; j< strArrHeaderFields.length; j++) {
                 objDataHashMap.put(strArrHeaderFields[j], strArrValues[j]);
            }

            //System.out.println( "objDataHashMap Count of Records ...." + objDataHashMap.size() );
            objAggregateData.put(i,objDataHashMap);

        }
        System.out.println( "objAggregateData Count of Records ...." + objAggregateData.size() );

        objAggregateData.forEach((k,v) -> {
            System.out.println(k + " : " + v );
        });

    } catch (Exception ex) {
        Logger.getLogger("FileProcessing").log(Level.SEVERE, null, ex);
    }
}