Writing Files in Kotlin

Here’s the translation of the Go code for writing files to Kotlin, along with explanations in Markdown format suitable for Hugo:

Writing files in Kotlin follows similar patterns to the ones we saw earlier for reading.

import java.io.File
import java.io.BufferedWriter

fun check(e: Exception?) {
    if (e != null) {
        throw e
    }
}

fun main() {
    // To start, here's how to dump a string (or just bytes) into a file.
    val d1 = "hello\nkotlin\n".toByteArray()
    try {
        File("/tmp/dat1").writeBytes(d1)
    } catch (e: Exception) {
        check(e)
    }

    // For more granular writes, open a file for writing.
    val f = File("/tmp/dat2").bufferedWriter()

    // It's idiomatic to use `use` for automatic resource management
    f.use { writer ->
        // You can write byte arrays as you'd expect.
        val d2 = byteArrayOf(115, 111, 109, 101, 10)
        writer.write(String(d2))
        println("wrote ${d2.size} bytes")

        // A write method for strings is also available.
        val n3 = writer.write("writes\n")
        println("wrote $n3 bytes")

        // BufferedWriter provides buffered writing.
        writer.write("buffered\n")
        println("wrote ${"buffered\n".length} bytes")

        // The `use` function automatically calls flush and close
    }
}

Try running the file-writing code.

$ kotlin writing-files.kt
wrote 5 bytes
wrote 7 bytes
wrote 9 bytes

Then check the contents of the written files.

$ cat /tmp/dat1
hello
kotlin
$ cat /tmp/dat2
some
writes
buffered

Next we’ll look at applying some of the file I/O ideas we’ve just seen to the stdin and stdout streams.

Random Numbers in Kotlin

Number Parsing in Kotlin

Learn X By Example

Title here

Writing Files in Kotlin