README

Welcome to kotlin-csv 👋

Version License: Apache License 2.0 CircleCI codecov CodeFactor

Pure Kotlin CSV Reader/Writer

Principals

1. Simple interface

  • easy to setup

  • use DSL so easy to read

2. No need to be aware of file close

  • on Java, we always need to close file. but it's boilerplate code and not friendly for non-JVM user.

  • provide interfaces which automatically close file without being aware.

3. Multiplatform (Planned in #15)

  • kotlin multiplatform project

Usage

Download

gradle DSL:

//gradle kotlin DSL
implementation("com.github.doyaaaaaken:kotlin-csv-jvm:0.10.4")
//gradle groovy DSL
implementation 'com.github.doyaaaaaken:kotlin-csv-jvm:0.10.4'

maven:

<dependency>
<groupId>com.github.doyaaaaaken</groupId>
<artifactId>kotlin-csv-jvm</artifactId>
<version>0.10.4</version>
</dependency>

Examples

CSV Read examples

Simple case

You can read csv file from String, java.io.File or java.io.InputStream object.

// read from `String`
val csvData: String = "a,b,c\nd,e,f"
val rows: List<List<String>> = csvReader().readAll(csvData)
// read from `java.io.File`
val file: File = File("test.csv")
val rows: List<List<String>> = csvReader().readAll(file)

Read with header

val csvData: String = "a,b,c\nd,e,f"
val rows: List<Map<String, String>> = csvReader().readAllWithHeader(csvData)
println(rows) //[{a=d, b=e, c=f}]

Read as Sequence

Sequence type allows to execute lazily. It starts to process each rows before reading all row data.

See detail about Sequence type on Kotlin official document.

csvReader().open("test1.csv") {
readAllAsSequence().forEach { row: List<String> ->
//Do something
println(row) //[a, b, c]
}
}
csvReader().open("test2.csv") {
readAllWithHeaderAsSequence().forEach { row: Map<String, String> ->
//Do something
println(row) //{id=1, name=doyaaaaaken}
}
}

NOTE:readAllAsSequence and readAllWithHeaderAsSequence methods can be only called inside open method lambda block. Because, input stream is closed outside open method lambda block.

Read line by line

If you want to handle line-by-line, you can do it by using open method. Use open method and then use readNext method inside nested block to read row.

csvReader().open("test.csv") {
readNext()
}

Customize

When you create CsvReader, you can choose read options.

// this is tsv reader's option
val tsvReader = csvReader {
charset = "ISO_8859_1"
quoteChar = '"'
delimiter = '\t'
escapeChar = '\\'
}

Opton

default value

description

charset

UTF-8

Charset encoding. The value must be supported by java.nio.charset.Charset.

quoteChar

"

Character used as quote between each fields.

delimiter

,

Character used as delimiter between each fields. Use "\t" if reading TSV file.

escapeChar

"

Character to escape quote inside field string. Normally, you don't have to change this option. See detail comment on ICsvReaderContext.

skipEmptyLine

false

If empty line is found, skip it or not (=throw an exception).

skipMissMatchedRow

false

If a invalid row which has different number of fields from other rows is found, skip it or not (=throw an exception).

CSV Write examples

Simple case

You can write csv simply, only one line. No need to call other methods. Also, You don't have to call use, close and flush method.

val rows = listOf(listOf("a", "b", "c"), listOf("d", "e", "f"))
csvWriter().writeAll(rows, "test.csv")
// if you'd append data on the tail of the file, assign `append = true`.
csvWriter().writeAll(rows, "test.csv", append = true)

You can also write csv file per each line. Also, You don't have to call use, close and flush method.

val row1 = listOf("a", "b", "c")
val row2 = listOf("d", "e", "f")
csvWriter().open("test.csv") {
writeRow(row1)
writeRow(row2)
writeRow("g", "h", "i")
writeRows(listOf(row1, row2))
}

Customize

When you create CsvWriter, you can choose write options.

val writer = csvWriter {
charset = "ISO_8859_1"
delimiter = '\t'
nullCode = "NULL"
lineTerminator = "\n"
outputLastLineTerminator = true
quote {
mode = WriteQuoteMode.ALL
char = '\''
}
}

Opton

default value

description

charset

UTF-8

Charset encoding. The value must be supported by java.nio.charset.Charset.

delimiter

,

Character used as delimiter between each fields. Use "\t" if reading TSV file.

nullCode

(empty string)

Character used when a written field is null value.

lineTerminator

\r\n

Character used as line terminator.

outputLastLineTerminator

true

Output line break at the end of file or not.

quote.char

"

Character to quote each fields.

quote.mode

CANONICAL

Quote mode. - CANONICAL: Not quote normally, but quote special characters (quoteChar, delimiter, line feed). This is the specification of CSV. - ALL: Quote all fields.

Miscellaneous

🤝 Contributing

Contributions, issues and feature requests are welcome! Feel free to check issues page. If you have question, feel free to ask in Kotlin slack's kotlin-csv room.

💻 Development

$ git clone [email protected]:doyaaaaaken/kotlin-csv.git
$ cd kotlin-csv
$ ./gradlew check

Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2019 doyaaaaaken. This project is Apache License 2.0 licensed.

This project is inspired ❤️ by scala-csv

This README was generated with ❤️ by readme-md-generator