Java read CSV file ,contents not write in new CSV file

Question

package com;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;
import com.opencsv.CSVWriter;
import com.opencsv.CSVReader;

public class Sample2 {
    public static void main(String args[]) throws IOException
    {
        CSVReader csvReader = null;  
        String[] employeeDetails ;        
        CSVWriter  csvWriter = new CSVWriter(new FileWriter("D:\\sample\\myfile.csv",true));
        csvReader = new CSVReader(new FileReader("D:\\sample\\source.csv"));          
        try
        {        

            employeeDetails = csvReader.readNext();               
            while ((employeeDetails = csvReader.readNext()) != null ) {               

                    System.out.println(Arrays.toString(employeeDetails));                   
                    csvWriter.writeNext(employeeDetails);
                }               

        }catch(Exception ee)
            {
                ee.printStackTrace();
            }
        }
}

I have my above java code It read data from source.csv file and also display in the console . It created myfile.csv ,but same contents it didn't write in the csv file Anyone have any idea on this

Answer 1

The issue is that you don't close your output resources, try this code:

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

try (CSVWriter csvWriter = new CSVWriter(new FileWriter("D:\\sample\\myfile.csv", true));
    CSVReader csvReader = new CSVReader(new FileReader("D:\\sample\\source.csv"));
    ) {

  while ((employeeDetails = csvReader.readNext()) != null) {

    System.out.println(Arrays.toString(employeeDetails));
    csvWriter.writeNext(employeeDetails);
  }
}
catch (Exception ee) {
  ee.printStackTrace(); //perhaps you should also log the error?
}
}

Also take a look at this question Is closing the resources always important?