Question

I am creating a csv file as follows:

public class check
{
public static void main(String [] args)
{
   generateCsvFile("/RMT/test.csv"); 
}

private static void generateCsvFile(String sFileName)
{
try
{
    FileWriter writer = new FileWriter(sFileName,false);

    writer.write("DisplayName");
    writer.write(',');
    writer.write("Age");
    writer.write('\n');

    writer.write("MKYONG");
    writer.write(',');
    writer.write("26");

    writer.write("YOUR NAME");
    writer.write(',');
    writer.write("29");

    writer.flush();
    writer.close();
}
catch(IOException e)
{
     e.printStackTrace();
} 
}

Here I am writing two lines in the file, but when I am writing the second line I want to replace the first line (the header) rather than append it. How can i do it? Can some help me?

Answer 1

I would read the csv data into memory and do the calculation, then write the result to the file.

if it won’t work for you somehow:

• you could load the file you are gonna write to, and read the 1st line( header), then append new calculated datasets (in memory), overwrite the file.

• if the header is fixed text, then save it as a variable then you don’t need to load the header from the file.

• if you need operate the file precisely, check out java.io.RandomAccessFile