基于@plirke示例代码和他的帮助,我编写了一个最终的工作代码。在这里分享它,这样它可能对有类似需求的人有用。

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.util.Random;

public class Demo1 {

public static String getRandomNumber() {

String CHARS = "1234567890";

StringBuilder random = new StringBuilder();

Random rnd = new Random();

while (random.length() < 18) // length of the random string.

{

int index = (int) (rnd.nextFloat() * CHARS.length());

random.append(CHARS.charAt(index));

}

String finaldata = random.toString();

return finaldata;

}

public static void main(String[] args) throws IOException {

File sourceCsvFile = null;

File finalCsvFile = null;

// String sourceCsvFileName = "";

sourceCsvFile = new File("C:\\MyData\\Input.csv");

finalCsvFile = new File("C:\\MyData\\Input_1.csv");

String line = "";

String cvsSplitBy = ",";

BufferedWriter writer = new BufferedWriter(new FileWriter(finalCsvFile));

try (BufferedReader br = new BufferedReader(new FileReader(sourceCsvFile))) // read the actual Source downloaded csv file

{

line = br.readLine(); // read only first line

String newFileLine = line + cvsSplitBy + "HashValue"; // append "," and new column

writer.write(newFileLine); // will be written as first line in new csv

writer.newLine(); // go to next line for writing next lines

while ((line = br.readLine()) != null) // this loop to write data for all lines except headers

{

newFileLine = line + cvsSplitBy + getRandomNumber(); // will add random numbers for each row

writer.write(newFileLine);

writer.newLine();

}

}

writer.close();

if(finalCsvFile.exists() && finalCsvFile.length() > 0)

{

System.out.println("New File with HashValue column created...");

if(sourceCsvFile.delete())

{

System.out.println("Old File deleted successfully...");

}

else

{

System.out.println("Failed to delete the Old file...");

}

}

else if (!finalCsvFile.exists())

{

System.out.println("New File with HashValue column not created...");

}

}

}