java - 使用 openCSV 用新值更新行

Question

我需要使用 openCSV 实用程序用新值更新一行。举例来说，我有以下 CSV 文件，我需要将包含 TestdminUsername1 和 TestdminUsername2 的行更新为 TestdminUsername1,Fail,Errors Found 和 TestdminUsername2，失败，发现错误分别。

TestdminUsername1,Pass,No Error
TestAdminUsername2,Pass,No Error
TestAdminUsername3,Pass,No Error
TestAdminUsername4,Pass,No Error
TestAdminUsername5,Pass,No Error
TestAdminUsername6,Pass,No Error
TestAdminUsername7,Pass,No Error
TestAdminUsername8,Pass,No Error
TestAdminUsername9,Pass,No Error
TestAdminUsername10,Pass,No Error

下面是我使用的代码片段:

import java.io.FileReader;
import java.io.FileWriter;
import java.util.Arrays;

import com.opencsv.CSVReader;
import com.opencsv.CSVWriter;

public class AppendToCSVExample
{
    @SuppressWarnings("resource")
    public static void main(String[] args) throws Exception
   {
      String csv = "D:\\data2.csv";
      CSVWriter writer = new CSVWriter(new FileWriter(csv, true));
      String [] record1 = "TestdminUsername1,Pass,No Error".split(",");
      String [] record2 = "TestAdminUsername2,Pass,No Error".split(",");
      String [] record3 = "TestAdminUsername3,Pass,No Error".split(",");
      String [] record4 = "TestAdminUsername4,Pass,No Error".split(",");
      String [] record5 = "TestAdminUsername5,Pass,No Error".split(",");
      String [] record6 = "TestAdminUsername6,Pass,No Error".split(",");
      String [] record7 = "TestAdminUsername7,Pass,No Error".split(",");
      String [] record8 = "TestAdminUsername8,Pass,No Error".split(",");
      String [] record9 = "TestAdminUsername9,Pass,No Error".split(",");
      String [] record10 = "TestAdminUsername10,Pass,No Error".split(",");

      writer.writeNext(record1);
      writer.writeNext(record2);
      writer.writeNext(record3);
      writer.writeNext(record4);
      writer.writeNext(record5);
      writer.writeNext(record6);
      writer.writeNext(record7);
      writer.writeNext(record8);
      writer.writeNext(record9);
      writer.writeNext(record10);

      writer.close();

      CSVReader reader = new CSVReader(new FileReader("D:\\data1.csv"), ',' , '"' , 1);

      String[] nextLine;
      while ((nextLine = reader.readNext()) != null) {
          if (nextLine != null) {
         //Verifying the read data here
         System.out.println(Arrays.toString(nextLine));
         String[] parts = Arrays.toString(nextLine).split(",");
         if (parts[0].toString().contains("TestdminUsername1")) {
             String [] recordTest = "TestdminUsername1, Fail, Errors found".split(",");
              //Which method in openCSV needs to be used to update recordTest value in the File data2.csv
             ;
         }
      }
    }
  }
}

Answer 1

我个人建议您打开第二个 CSVWriter 到新文件 (data3.csv)，当您从 data1 读取数据时，写入 data3 更改需要修改的数据。这样，如果您因某种原因出现故障，您仍然可以保留原始文件。最后，如果您只想要一个文件，可以删除 data1 并将 data3.csv 重命名为 data1.csv。

之前有一个问题，有人试图同时读取和写入同一个文件( Reading from a CSV file and writing to a new CSV file using openCSV in java )，但我再次建议不要这样做，以防出现错误。