Kotlin Native how to convert ByteArray to String?

Question

I was playing with the kotlin-native samples. I wonder how I could get String from pinned ByteArray. Just want to print it in the console.

What is the encoding that was used to convert chars to bytes in that array? — Ilya, Mar 25 '18 at 20:06

Willi Mentzel · Answer 1 · 2019-02-05T19:40:18.610

28

If you need a solution for the JVM, since stringFromUtf8 is only available for the native platform, use toString with a Charset as argument:

val byteArray = "Hello World".toByteArray(Charsets.UTF_8)   
val str = byteArray.toString(Charsets.UTF_8)

If you specifically only want to target native, use Sin's solution.

edited Feb 05 '19 at 19:40

answered Mar 24 '18 at 18:08

Willi Mentzel

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Sin · Accepted Answer · 2019-02-15T09:04:06.603

10

It seems that this API has changed

Now just use this: string.toUtf8(start, end)

https://github.com/JetBrains/kotlin-native/commit/cba7319e982ed9ba2dceb517a481cb54ed1b9352#diff-45a5f8d37067266e27b76d1b68f01173

Legacy version:

Use stringFromUtf8

/**
 * Converts an UTF-8 array into a [String]. Replaces invalid input sequences with a default character.
 */
fun ByteArray.stringFromUtf8(start: Int = 0, size: Int = this.size) : String =
        stringFromUtf8Impl(start, size)

See here.

And if the byteArray is like CPointer<ByteVar> by interoperating C APIs, pleace use .toKString() in Kotlin-Native

edited Feb 15 '19 at 09:04

answered Mar 24 '18 at 18:29

Sin

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Thanks to @Willi Mentzel for adding the reference for`stringFromUtf8`'s source code. – Sin Mar 25 '18 at 08:30
Very thanks. But I can't find the source of `stringFromUtf8` in the referenced link ([here: StringBuilder.kt](https://github.com/JetBrains/kotlin-native/blob/master/runtime/src/main/kotlin/kotlin/text/StringBuilder.kt)). – Mir-Ismaili Feb 11 '19 at 01:06
This API has been deprecated......ReplaceWith("string.toUtf8(start, end)" https://github.com/JetBrains/kotlin-native/commit/cba7319e982ed9ba2dceb517a481cb54ed1b9352#diff-45a5f8d37067266e27b76d1b68f01173 – Sin Feb 15 '19 at 09:01
The question was about converting ByteArray to String? How string.toUtf8(start, end) could help me? – kilg Sep 30 '21 at 12:02

score 0 · Answer 3 · answered Sep 03 '23 at 08:25

0

In my case this worked:

ByteArray.decodeToString()
ByteArray.toString(Charsets.UTF_8)
ByteArray.commonToUtf8String()

They all gave the same result.

answered Sep 03 '23 at 08:25

Maxim

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score -1 · Answer 4 · answered Sep 13 '22 at 14:12

-1

The OKIO library has a helper method for this commonToUtf8String

One can simply copy the method code don't need to add the entire lib just for this.

answered Sep 13 '22 at 14:12

Calin

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score -1 · Answer 5 · answered Nov 26 '22 at 14:38

Another solution that could be used everyone but especially makes sense looking for a Kotlin Multiplatform solution and using ktor library already is using io.ktor.utils.io.core.String function directly without adding extra third pary library or extra actual class implementation. For example:

Your build.gradle.kts for all platforms:

implementation("io.ktor:ktor-client-core:${Versions.ktor}")
implementation("io.ktor:ktor-client-android:${Versions.ktor}")
implementation("io.ktor:ktor-client-apache:${Versions.ktor}")
implementation("io.ktor:ktor-client-ios:${Versions.ktor}")

Then use it

io.ktor.utils.io.core.String(byteArray, offset, length, Charsets.UTF_8)

Kotlin Native how to convert ByteArray to String?

5 Answers5

It seems that this API has changed

Legacy version:

Linked