Java：如何比较CSV文件的列并打印特定行

Question

我是Java编程的新手，我的任务是解析CSV文件并通过比较列打印出CSV文件的正确行，例如打印的行需要有唯一的第1和第2列，第3列必须包含“no”，第4列的值大于或等于12。

共5列。

此外，我不允许使用任何为您解析CSV的库。

private static String[] routerData;

public static void main(String [] args)  {

    // Input of file which needs to be parsed
    String csvFile = "./sample.csv";
    BufferedReader csvReader = null;

    // Data split by ',' in CSV file
    String line = null;
    String csvSplitBy = ",";

    try {

        // Create the CSV file reader
        csvReader = new BufferedReader(new FileReader(csvFile));
        while ((line = csvReader.readLine()) !=null) {

            routerData = line.split(csvSplitBy, -1);
            System.out.println(routerData[0] + ", " + routerData[1] + ", " + routerData[2] + ", " + routerData[3] + ", " + routerData[4]);

        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (csvReader != null) {
            try {
                csvReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Name,IP,Working?,Version,Comments
name,0.0.0.0,No,11.2,Some GUI Bugs
name2,0.1.2.0,Yes,12.3,
name,0.0.1.0,Yes,12.2,Case broken,
name4,0.0.0.0,no,10.3

我不确定使用什么数据结构来比较列。

我非常感谢任何建议！

Answer 1

您的问题中的要求相当混乱，如果没有示例CSV数据，事情不会变得更容易。混淆部分与关于唯一性的第1列和第2列数据有关。你认为什么是独一无二的？

A）从列1和/或列2包含的字符串或数值在任何其他CSV文件行中没有重复（在其相应列中没有重复）的意义上来说，它是否是唯一的？

B）还是在列1和/或列2包含一个字符串或数值的意义上是唯一的，该字符串或数值本身是唯一的，并且可以在其他CSV文件行中找到（在其各自的列中允许重复）？

Jack,Flash,yes,14,Unknown Value
Bob,Stick,no,11,Unknown Value
Jack,Flash,no,22,Unknown Value
Fred,Frog,yes,6,Unknown Value
Bob,Stick,no,32,Unknown Value
Tracey,Jones,no,17,Unknown Value
Fred,Frog,no,23,Unknown Value
John,Brown,no,12,Unknown Value
Bob,Stick,yes,88,Unknown Value

下面是示例代码：

ArrayList<String> resultList = new ArrayList<>();
ArrayList<String> linesList = new ArrayList<>();
// Input of file which needs to be parsed
String csvFile = "sample.csv";
BufferedReader csvReader;

// Data split by ',' in CSV file
String csvSplitBy = ",";
try {
    // Read the CSV file into an ArrayList array for easy processing.
    String line;
    csvReader = new BufferedReader(new FileReader(csvFile));
    while ((line = csvReader.readLine()) !=null) {
        linesList.add(line);
    }
    csvReader.close();
} 
catch (IOException e) { e.printStackTrace(); } 

// Process each CSV file line which is now contained within
// the linesList list Array
for (int i = 0; i < linesList.size(); i++) {
    String[] data = linesList.get(i).split(csvSplitBy);
    String col1 = data[0];
    String col2 = data[1];
    String col3YesNo = data[2];
    //int col4Value = Integer.parseInt(data[3]);  //WAS THIS
    double col4Value = Double.parseDouble(data[3]); // *** SHOULD BE ***
    String col5Unknown = data[4];

    // Determine if Column 1 and Column 2 data for the 
    // current line is unique to the entire CSV file.
    boolean columns1And2AreUnique = true;
    for (int j = 0; j < linesList.size(); j++) {
        String[] tmp = linesList.get(j).split(csvSplitBy);
        // Make sure we don't process the same line we are on...
        if (j != i) {
            if (col1.equals(tmp[0]) || col2.equals(tmp[1])) { 
                columns1And2AreUnique = false; 
                break;
            }
        }
    }
    if (columns1And2AreUnique && col3YesNo.equalsIgnoreCase("no") && col4Value >= 12.0) {
        resultList.add(linesList.get(i));
    }
}

// Display the determined results from the CSV file.
if (resultList.isEmpty()) {
    System.out.println("There could be no data results gathered from the supplied\n"
                     + "CSV file which meets the required criteria.");
}
else {
    System.out.println("Column 1\tColumn 2\tColumn 3\tColumn 4\tColumn 5");
    System.out.println("================================================"
                     + "========================\n");
    String padString = "        "; //Used for simple space padding in display
    for (int i = 0; i < resultList.size(); i++) {
        String[] tmp = resultList.get(i).split(csvSplitBy);
        System.out.println(tmp[0] + padString.substring(tmp[0].length()) + "\t" 
                         + tmp[1] + padString.substring(tmp[1].length()) + "\t" 
                         + tmp[2] + padString.substring(tmp[2].length()) + "\t"
                         + tmp[3] + padString.substring(tmp[3].length()) + "\t"
                         + tmp[4]);
    }
}

编辑：现在您已经发布了CSV文件中的一些示例数据...

好吧，我非常接近于我的柱状CSV数据类型假设，但确实需要对代码进行更改，因为我现在知道第4个数据列包含双数据类型值。

int col4Value = Integer.parseInt(data[3]);

double col4Value = Double.parseDouble(data[3]);