How to write Data to a CSV File using OpenCSV

CSV (Comma-Separated Values) files are a standard way of storing tabular data like spreadsheets or database exports. Whether you’re exporting reports, saving logs, or generating data for third-party integration, the ability to write CSV files efficiently is essential for many Java applications.

In this tutorial, you’ll learn how to write data to a CSV file in Java using OpenCSV — a lightweight, easy-to-use library for reading and writing CSVs. We’ll walk you through creating headers, adding rows, and exporting to a clean .csv file.

This tutorial is beginner-friendly and ideal for backend developers, data engineers, or anyone building Java applications that need to output structured data.

⚙️ Add OpenCSV to Your Maven Project

First, include OpenCSV in your pom.xml file:

<groupid>com.opencsv</groupid>

<artifactid>opencsv</artifactid>

</dependency>

Make sure to refresh your Maven project to download the dependency.

🧾 Use Case: Writing Employee Data to CSV

We’ll write the following employee data to a file called employees.csv:

ID	Name	Department
101	Alice	Engineering
102	Bob	Marketing
103	Charlie	Finance

🧑‍💻 Java Code Example

package com.kscodes.opencsv;

import com.opencsv.CSVWriter;

import java.io.FileWriter;

import java.io.IOException;

public class WriteCSVExample {

public static void main(String[] args) {

String filePath = "employees.csv";

try (CSVWriter writer = new CSVWriter(new FileWriter(filePath))) {

// Writing header

String[] header = { "ID", "Name", "Department" };

writer.writeNext(header);

// Writing rows

String[ ] emp1 = { "101", "Alice", "Engineering" };

String[ ] emp2 = { "102", "Bob", "Marketing" };

String[ ] emp3 = { "103", "Charlie", "Finance" };

writer.writeNext(emp1);

writer.writeNext(emp2);

writer.writeNext(emp3);

System.out.println("CSV file written successfully to " + filePath);

} catch (IOException e) {

System.err.println("Error writing CSV: " + e.getMessage());

e.printStackTrace();

}

📝 Output (employees.csv)

ID,Name,Department

101,Alice,Engineering

102,Bob,Marketing

103,Charlie,Finance

📌 Key Points

CSVWriter handles commas, quotes, and escape characters for you.
writeNext(String[]) is used to write a single row at a time.

💡 Tip: OpenCSV also supports custom separators and quote characters. This is useful if you’re working with ; or | delimited files.

📚 Real-World Applications

Writing CSV files is useful for:

Exporting user reports
Generating product feeds for e-commerce
Creating logs for data processing pipelines
Interfacing with legacy systems that consume CSV

OpenCSV makes it easy and safe by abstracting the low-level logic you’d otherwise write manually.

🧠 Conclusion

In this tutorial, you learned how to write Data to a CSV File using OpenCSV. From defining headers to adding rows, the process is straightforward and highly customizable.

By leveraging OpenCSV, you can handle edge cases like quotes, newlines, or special characters without any additional effort. If you’re exporting data in Java, OpenCSV should be your go-to tool.