How to Read a Simple CSV File using OpenCSV

CSV (Comma-Separated Values) is one of the most widely used data exchange formats. Whether you’re importing data from spreadsheets, integrating with third-party systems, or processing simple reports, chances are you’ll come across CSV files in your Java projects.

However, reading CSV files manually with BufferedReader and String.split() can quickly become messy, especially when dealing with quoted values, commas within fields, or line breaks. This is where OpenCSV shines.

In this tutorial, you’ll learn how to read a simple CSV file using OpenCSV in a clean and reliable way. This guide is perfect for beginners working on Java console applications, data loaders, or backend services.

Read CSV file in Java using OpenCSV

⚙️ Setting Up OpenCSV in Maven

To get started, add the following dependency in your pom.xml. This will bring in the OpenCSV library, which handles CSV parsing under the hood.



    com.opencsv
    opencsv
    5.9

Make sure your Java version is Java 8 or higher.

📁 Sample CSV File

Create a file named employees.csv in your project root (or resources folder) with the following content:


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

Each line represents a record, and fields are separated by commas. The first row is a header row.

🧑‍💻 Java Code to Read CSV Using OpenCSV


package com.kscodes.opencsv;

import com.opencsv.CSVReader;

import java.io.FileReader;
import java.util.List;

public class ReadCSVExample {
    public static void main(String[] args) {
        String filePath = "employees.csv";

        try (CSVReader reader = new CSVReader(new FileReader(filePath))) {
            List records = reader.readAll();

            for (int i = 0; i < records.size(); i++) {
                String[] row = records.get(i);
                if (i == 0) {
                    System.out.println("Header: " + String.join(" | ", row));
                } else {
                    System.out.printf("Employee -> ID: %s | Name: %s | Dept: %s%n", row[0], row[1], row[2]);
                }
            }

        } catch (Exception e) {
            System.err.println("Error reading CSV file: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

🔍 Code Explanation

  • CSVReader: This class simplifies reading CSV files, handling comma delimiters and quoted fields automatically.
  • readAll(): Loads the entire file into memory. Great for small-to-medium files.
  • Loop logic: We print the header differently to give meaningful structure to the output.
  • Error Handling: It’s essential to catch exceptions like FileNotFoundException or malformed CSV issues.

✅ Tip: For large files, use readNext() inside a while loop instead of readAll() to avoid high memory usage.

🧠 Real-world Use Cases

Reading CSV files is common in:

  • Importing user data into admin panels
  • Loading configuration settings
  • Processing log or audit files
  • Migrating legacy data into a modern app
  • Parsing product feeds for e-commerce apps

OpenCSV makes these tasks not only easier but also safer and more maintainable.

🧾 Output Example


Header: ID | Name | Department
Employee -> ID: 101 | Name: Alice | Dept: Engineering
Employee -> ID: 102 | Name: Bob | Dept: Marketing
Employee -> ID: 103 | Name: Charlie | Dept: Finance

🧩 Conclusion

Reading CSV files manually can lead to bugs, especially when data gets messy. OpenCSV gives Java developers a robust and flexible tool to handle CSV files with ease. In this post, you learned how to:

  • Set up OpenCSV in a Maven project
  • Create and read a sample CSV file
  • Use CSVReader to parse rows
  • Handle headers and display results

This is just the beginning! In future posts, you’ll explore writing CSV files, mapping to Java beans, handling custom delimiters, and more advanced operations.