Java – Writing strings to a CSV file

The Problem (Q-score 5, ranked #118th of 303 in the Excel VBA archive)

The scenario as originally posted in 2015

I am trying to write data to a csv file with java, however when I try opening the produced file with excel I am getting an error saying the file is corrupt. Upon opening the file in notepad it looks to be formatted correctly so I’m not sure what the issue is. I am using the FileWriter class to output the data to the file.

FileWriter writer = new FileWriter("test.csv");

writer.append("ID");
writer.append(',');
writer.append("name");
writer.append(',');
...
writer.append('n');

writer.flush();
writer.close();

Do I need to use some library in java in order to print to a csv file? I presumed you could just do this natively in java as long as you used the correct formatting.

Appreciate the help,

Shaw

Why community consensus is tight on this one

Across 303 Excel VBA entries in the archive, the accepted answer here holds solid answer (above median) status — meaning voters are unusually aligned on the right fix.

The Verified Solution — solid answer (above median) (+14)

25-line Excel VBA pattern (copy-ready)

According to this Microsoft Documentation, the error is shown because of the uppercase word "ID" as first row. Change it to "id" and it works as expected.

This is weird. But yeah!

Also trying to minimize file access by using file object less.

I tested and the code below works perfect.

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;


public class CSV {
    public static void main(String[]args) throws FileNotFoundException{
        PrintWriter pw = new PrintWriter(new File("test.csv"));
        StringBuilder sb = new StringBuilder();
        sb.append("id");
        sb.append(',');
        sb.append("Name");
        sb.append('n');

        sb.append("1");
        sb.append(',');
        sb.append("Prashant Ghimire");
        sb.append('n');

        pw.write(sb.toString());
        pw.close();
        System.out.println("done!");
    }
}

When to Use It — classic (2013–2016)

Ranked #118th in its category — specialized fit

This pattern sits in the 96% tail relative to the top answer. Reach for it when your scenario closely matches the question title; otherwise browse the Excel VBA archive for a higher-consensus alternative.

What changed between 2015 and 2026

The answer is 11 years old. The Excel VBA object model has been stable across Office 2013, 2016, 2019, 2021, 365, and 2024/2026 LTSC, so the pattern still compiles. Changes that might affect you: 64-bit API declarations (use PtrSafe), blocked macros in downloaded files (Mark-of-the-Web), and the shift toward Office Scripts for web-first workflows.