Read a CSV file, copy the CSV file data, concatenate two columns from original file and write it to another csv file

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

public class CSVModifier {

public static void main(String[] args) {

String line;

String inputFilePath = "F:\\DOCS\\test_03072024.csv";

String outputFilePath = "F:\\DOCS\\updated_test_03072024.csv";

try  {

BufferedReader br = new BufferedReader(new FileReader(inputFilePath));

BufferedWriter bw = new BufferedWriter(new FileWriter(outputFilePath));

// Read the header

String header = br.readLine();

if (header != null) {

String[] headers = header.split(",");

int appIndex = -1;

int roleNameIndex = -1;

// Find the indices of "app" and "Role Name"

for (int i = 0; i < headers.length; i++) {

if (headers[i].trim().equalsIgnoreCase("app")) {

appIndex = i;

} else if (headers[i].trim().equalsIgnoreCase("Role Name")) {

roleNameIndex = i;

}

}

// Check if both columns were found

if (appIndex == -1 || roleNameIndex == -1) {

throw new IllegalArgumentException(

"Input CSV does not contain required columns 'Service' and 'Role Name'");

}

// Add the new column to the header

header += ",app|RoleName";

bw.write(header);

bw.newLine();

// Read and process each line

while ((line = br.readLine()) != null) {

String[] columns = line.split(",");

String app = columns[appIndex];

String roleName = columns[roleNameIndex];

// Concatenate "app" and "Role Name"

String newColumn = app + "|" + roleName;

// Add the new column to the line

line += "," + newColumn;

bw.write(line);

bw.newLine();

}

}

bw.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}