Kotlin write file
last modified January 29, 2024
This article shows how to write to a file in Kotlin.
Kotlin is a statically-typed programming language that runs on Java Virtual Machine.
The tutorial presents four examples that write to a file in Kotlin.
Kotlin write file with PrintWriter
PrintWriter prints formatted representations of objects to a
text-output stream.
package com.zetcode
import java.io.File
fun main() {
val fileName = "src/resources/myfile.txt"
val myfile = File(fileName)
myfile.printWriter().use { out ->
out.println("First line")
out.println("Second line")
}
println("Writed to file")
}
The example writes two lines to a file with PrintWriter.
val fileName = "src/resources/myfile.txt"
We write to src/resources/myfile.txt file.
myfile.printWriter().use { out ->
The printWriter returns a PrintWriter for writing the
content to the file. The use method executes the given block
function on the file and then closes it.
out.println("First line")
out.println("Second line")
With println we write a string to the file including a terminating
new line.
Kotlin write file with BufferedWriter
BufferedWriter writes text to a character-output stream, buffering
characters to provide for more efficient writing of single characters, arrays,
and strings.
package com.zetcode
import java.io.File
fun main() {
val fileName = "src/resources/myfile.txt"
val myfile = File(fileName)
myfile.bufferedWriter().use { out ->
out.write("First line\n")
out.write("Second line\n")
}
println("Writed to file")
}
The example writes two lines to a file with BufferedWriter.
myfile.bufferedWriter().use { out ->
The bufferedWriter returns a BufferedWriter
for writing the content to the file. The use method
executes the given block function on the file and then closes it.
Kotlin write file with writeText
The writeText is a Kotlin File extension function
which writes text encoded using UTF-8 or other charset to the file. If this file
exists, it becomes overwritten.
package com.zetcode
import java.io.File
fun main() {
val fileName = "src/resources/myfile3.txt"
val myfile = File(fileName)
val content = "Today snow is falling."
myfile.writeText(content)
println("Writed to file")
}
The example writes to a file with Kotlin writeText extension
function.
Kotlin write file with writeText
The Files.write writes bytes to a file.
package com.zetcode
import java.io.File
import java.nio.file.Files
import java.nio.file.StandardOpenOption
fun main() {
val fileName = "src/resources/myfile.txt"
val myfile = File(fileName)
val content = "Today snow is falling.\n"
Files.write(myfile.toPath(), content.toByteArray(), StandardOpenOption.APPEND)
}
The example writes to a file with Kotlin Files.write extension
function.
Files.write(myfile.toPath(), content.toByteArray(), StandardOpenOption.APPEND)
The first parameter of the Files.write is the Path
to the file, the second is the byte array to write, and the third parameter
are the options specifying how the file is opened.
In this article we have shown how to write to a file in Kotlin.
Source
Kotlin reference documentation
Author
List all Kotlin tutorials.