Delete files and subdirectories in a directory in Kotlin

This post will discuss how to delete files and subdirectories in a directory in Kotlin.

The standard function to delete the specified file or directory in Kotlin is File.delete(). There are several options to “conditionally” delete files and subdirectories within a directory using this function. For instance,

1. To delete only regular files within the root directory, you can do as follows.

import java.io.File

fun deleteDirectory(directory: File) {

for (file in directory.listFiles()) {

if (!file.isDirectory) {

file.delete()

}

fun main() {

val directory = File("/path/to/dir")

deleteDirectory(directory)

}

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Note that all subdirectories remain untouched. You can replace the for loop with the stdlib operations filterNot{}.forEach{}.

import java.io.File

fun deleteDirectory(directory: File) {

directory.listFiles()

.filterNot { it.isDirectory }

.forEach { it.delete() }

}

fun main() {

val directory = File("/path/to/dir")

deleteDirectory(directory)

}

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2. To delete a subdirectory with the File.delete() function, it should be empty. The idea is to recursively delete all files within the subdirectory, before deleting the subdirectory itself. This is demonstrated below:

import java.io.File

import java.util.*

fun deleteDirectory(directory: File) {

for (file in directory.listFiles()) {

if (file.isDirectory) {

deleteDirectory(file)

} else {

file.delete()

}

fun main() {

val directory = File("/path/to/dir")

deleteDirectory(directory)

}

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3. Alternatively, to delete the main directory as well (and all its contents), use the Files.walk() function.

import java.nio.file.Files

import java.nio.file.Path

fun deleteDirectory(directory: Path?) {

Files.walk(directory)

.sorted(Comparator.reverseOrder())

.map { it.toFile() }

.forEach { it.delete() }

}

fun main() {

val directory = Path.of("/path/to/dir")

deleteDirectory(directory)

}

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If you need to delete “only files” from the directory and all its subdirectories, apply a filter as follows:

import java.io.File

import java.nio.file.Files

fun deleteDirectory(directory: File) {

Files.walk(directory.toPath())

.filter { Files.isRegularFile(it) }

.map { it.toFile() }

.forEach { it.delete() }

}

fun main() {

val directory = File("/path/to/dir")

deleteDirectory(directory)

}

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That’s all about deleting files and subdirectories in a directory in Kotlin.

Delete files and subdirectories in a directory in Kotlin

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