Working with CSV in Kotlin: Libraries and Examples |…

Working with CSV in Kotlin: Libraries and Practical Examples

The CSV (Comma-Separated Values) format remains one of the most popular ways to exchange tabular data. In the Kotlin language, which is actively used for Android development, backend (Ktor, Spring Boot), and scripting, there are several convenient libraries for working with CSV. In this article, we will cover three main approaches: the lightweight kotlin-csv library, the powerful OpenCSV, and the classic Apache Commons CSV.

1. kotlin-csv Library (Recommended)

This is a pure Kotlin solution that does not require additional Java dependencies. It is ideal for projects where conciseness and type safety are important.

Installation (Gradle)

// build.gradle.ktsimplementation("com.github.doyaaaaaken:kotlin-csv-jvm:1.9.3")

Reading CSV

The library supports automatic delimiter detection, quote escaping, and headers.

import com.github.doyaaaaaken.kotlincsv.dsl.csvReader

fun readCsvExample() {    val csvData = """        name,age,city        Alice,30,New York        Bob,25,London    """.trimIndent()

    val rows: List<List<String>> = csvReader().readAll(csvData)

    rows.forEach { row ->        println("Name: ${row[0]}, Age: ${row[1]}, City: ${row[2]}")    }}

// Reading with headersfun readWithHeaders() {    val data = csvReader().readAllWithHeader(csvData)    data.forEach { row ->        println("${row["name"]} is ${row["age"]} years old")    }}

Writing CSV

import com.github.doyaaaaaken.kotlincsv.dsl.csvWriter

fun writeCsvExample() {    val rows = listOf(        listOf("Product", "Price", "Quantity"),        listOf("Laptop", "1200", "5"),        listOf("Mouse", "25", "50")    )

    csvWriter().writeAll(rows)    // Console output:    // Product,Price,Quantity    // Laptop,1200,5    // Mouse,25,50}

2. OpenCSV (for Complex Scenarios)

OpenCSV is a mature Java library that works great in Kotlin. It supports mapping to data classes, custom delimiters, and streaming processing of large files.

Installation

implementation("com.opencsv:opencsv:5.9")

Reading with Mapping to a Data Class

import com.opencsv.bean.CsvToBeanBuilderimport java.io.StringReader

data class Person(    @CsvBindByName(column = "name")    val name: String,    @CsvBindByName(column = "age")    val age: Int,    @CsvBindByName(column = "city")    val city: String)

fun readWithOpenCsv() {    val csv = """        name,age,city        Alice,30,New York        Bob,25,London    """.trimIndent()

    val beans: List<Person> = CsvToBeanBuilder<Person>(StringReader(csv))        .withType(Person::class.java)        .build()        .parse()

    beans.forEach { println(it) }    // Person(name=Alice, age=30, city=New York)    // Person(name=Bob, age=25, city=London)}

Writing with Headers

import com.opencsv.bean.StatefulBeanToCsvimport com.opencsv.bean.StatefulBeanToCsvBuilderimport java.io.StringWriter

fun writeWithOpenCsv() {    val people = listOf(        Person("Charlie", 35, "Paris"),        Person("Diana", 28, "Tokyo")    )

    val writer = StringWriter()    val beanToCsv: StatefulBeanToCsv<Person> = StatefulBeanToCsvBuilder<Person>(writer)        .build()    beanToCsv.write(people)

    println(writer.toString())    // name,age,city    // Charlie,35,Paris    // Diana,28,Tokyo}