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Working With CSV Files in Java Using Apache Commons CSV

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Working With CSV Files in Java Using Apache Commons CSV

Need to read CSV files quickly and efficiently in your Java projects? Let's get Apache Commons CSV added to your setup and see it in action.

· Java Zone ·
Free Resource

How do you break a Monolith into Microservices at Scale? This ebook shows strategies and techniques for building scalable and resilient microservices.

The Apache Commons CSV library is a Java library that can be used to read and write CSV files in a very simple and easy way. Another advantage is that this Java library is open source and freely available to use.

First, we need to add the library to your project.

To add it a Maven dependency, you just need to add this dependency to your pom.xml file:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-csv</artifactId>
    <version>1.5</version>
</dependency>

 

Or, to add it as a Gradle dependency, you can just add this to your dependencies within the build.gradle file:

compile "org.apache.commons:commons-csv:1.5"

 

Let's start by generating a simple CSV file — student.csv — in the following program.

Our program to generate a simple CSV file:

import java.io.IOException;
import java.io.Writer;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;

public class BasicCsvWriter {
    public static void main(String[] args) {
        try {

            //We have to create the CSVPrinter class object 
            Writer writer = Files.newBufferedWriter(Paths.get("student.csv"));
            CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT.withHeader("Student Name", "Fees"));

            //Writing records in the generated CSV file
            csvPrinter.printRecord("Akshay Sharma", 1000);
            csvPrinter.printRecord("Rahul Gupta", 2000);
            csvPrinter.printRecord("Jay Karn", 3000);

            //Writing records in the form of a list
            csvPrinter.printRecord(Arrays.asList("Dev Bhatia", 4000));

            csvPrinter.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}


This program generates the student.csv file with the content as follows:

Student Name, Fees
Akshay Sharma,1000 
Rahul Gupta,2000
Jay Karn,3000
Dev Bhatia,4000

 

Let's now read the content of the generated CSV file using the following program:

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;

public class BasicCsvReader {

    public static void main(String[] args) throws IOException {
        BufferedReader reader = Files.newBufferedReader(Paths.get("student.csv"));
        CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT.withHeader("Student Name", "Fees").withIgnoreHeaderCase().withTrim());

        for (CSVRecord csvRecord: csvParser) {

            // Accessing Values by Column Index
            String name = csvRecord.get(0);

            //Accessing the values by column header name
            String fees = csvRecord.get("fees");

            //Printing the record 
            System.out.println("Record Number - " + csvRecord.getRecordNumber());
            System.out.println("Name : " + name);
            System.out.println("Fees : " + fees);
            System.out.println("\n\n");
        }
    }
}

 

The output will be generated on the console as follows:

Record Number - 1
Name : Akshay Sharma
Fees : 1000

Record Number - 2
Name : Rahul Gupta
Fees : 2000

Record Number - 3
Name : Jay Karn
Fees : 3000

Record Number - 4
Name : Dev Bhatia
Fees : 4000

 

How do you break a Monolith into Microservices at Scale? This ebook shows strategies and techniques for building scalable and resilient microservices.

Topics:
java ,apache commons csv ,csv files ,tutorial

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