Read CSV line-by-line in Kotlin

Question

I'm writing a simple import application and need to read a CSV file, show result in a grid and show corrupted lines of the CSV file in another grid.

Is there any built-in lib for it or any easy pythonic-like way?

I'm doing it on android.

Answer 1

[Edit October 2019] A couple of months after I wrote this answer, Koyama Kenta wrote a Kotlin targeted library which can be found at https://github.com/doyaaaaaken/kotlin-csv and which looks much better to me than opencsv.

Example usage: (for more info see the github page mentioned)

import com.github.doyaaaaaken.kotlincsv.dsl.csvReader  fun main() {     csvReader().open("src/main/resources/test.csv") {         readAllAsSequence().forEach { row ->             //Do something             println(row) //[a, b, c]         }     } } 

For a complete minimal project with this example, see https://github.com/PHPirates/kotlin-csv-reader-example

Old answer using opencsv:

As suggested, it is convenient to use opencsv. Here is a somewhat minimal example:

// You can of course remove the .withCSVParser part if you use the default separator instead of ; val csvReader = CSVReaderBuilder(FileReader("filename.csv"))         .withCSVParser(CSVParserBuilder().withSeparator(';').build())         .build()  // Maybe do something with the header if there is one val header = csvReader.readNext()  // Read the rest var line: Array<String>? = csvReader.readNext() while (line != null) {     // Do something with the data     println(line[0])      line = csvReader.readNext() } 

As seen in the docs when you do not need to process every line separately you can get the result in the form of a Map:

import com.opencsv.CSVReaderHeaderAware import java.io.FileReader  fun main() {     val reader = CSVReaderHeaderAware(FileReader("test.csv"))     val resultList = mutableListOf<Map<String, String>>()     var line = reader.readMap()     while (line != null) {         resultList.add(line)         line = reader.readMap()     }     println(resultList)     // Line 2, by column name     println(resultList[1]["my column name"]) } 

Dependency for Gradle: compile 'com.opencsv:opencsv:4.6' or for Gradle Kotlin DSL: compile("com.opencsv:opencsv:4.6") (as always, check for latest version in docs).