How to convert a string to byte array in Kotlin

How to convert a string to byte array in Kotlin:

In this post, we will learn how to convert a string to a byte array in Kotlin. The String class provides a method called toByteArray in Kotlin that we can use to convert a string to a byte array. We will learn the syntax of this method and how to use it to convert a string to byte array.

Syntax of toByteArray:

The toByteArray method is defined as like below:

fun str.toByteArray(charset: Charset = Charsets.UTF_8): ByteArray

This method can be called on any string variable. It takes one optional parameter. This is the character set to use for the string-byte array conversion. By default, it is UTF-8.

It returns a ByteArray.

Example of toByteArray:

Let’s try the toByteArray method with an example:

fun main() {
    val givenString = "Hello World !!"
    val byteArray = givenString.toByteArray()

    println("Byte Array: ${byteArray.contentToString()}")
}

Here, we are converting the string givenString to a byte array. The contentToString() method returns a string representation of the byte array.

If you run this program, it will print:

Byte Array: [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 32, 33, 33]

We can also convert the byte array to a string to check if the conversion is correct.

fun main() {
    val givenString = "Hello World !!"
    val byteArray = givenString.toByteArray()

    println("Byte Array: ${byteArray.contentToString()}")
    println("Original String: ${byteArray.toString(Charsets.UTF_8)}")
}

The second print statement will print the original string. We are passing Charsets.UTF_8 to the toString() method as this is the default Charsets used with toByteArray.

Example to use toByteArray with different Charsets:

Let’s try toByteArray with a different Charsets:

fun main() {
    val givenString = "Hello World !!"
    val byteArray = givenString.toByteArray(Charsets.US_ASCII)

    println("Byte Array: ${byteArray.contentToString()}")
    println("Original String: ${byteArray.toString(Charsets.US_ASCII)}")
}

It uses US_ASCII. The program will print the same output as we are printing the string representation of the byte array. The byte array data will be different.

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How to convert a string to byte array in Kotlin