Right shift operator for byte in kotlin

Question

I have next code in java:

private final static char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
public static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    for (int j = 0; j < bytes.length; j++) {
    int v = bytes[j] & 0xFF;
        hexChars[j * 2] = HEX_ARRAY[v >>> 4];
        hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
    }

    return new String(hexChars);
}

I want to convert this code to kotlin. Autoconverting gave next result:

fun bytesToHex(bytes: ByteArray): String {
    val hexChars = CharArray(bytes.size * 2)
    for (j in bytes.indices) {
        val v = bytes[j] and 0xFF
        hexChars[j * 2] = HEX_ARRAY[v.ushr(4)]
        hexChars[j * 2 + 1] = HEX_ARRAY[v and 0x0F]
    }

    return String(hexChars)
}

but there is no function ushr for type Byte in kotlin. I've tried convert v to Int and shift this value and convert it again to Byte like (v.toInt().ushr(4) as Byte).toInt() . But it gives wrong result. What is the correct way to convert this function into kotlin.

Answer 1

You can convert bytes[j] to an integer and then the code works:

private val HEX_ARRAY = "0123456789ABCDEF".toCharArray()

fun bytesToHex(bytes: ByteArray): String {
    val hexChars = CharArray(bytes.size * 2)
    for (j in bytes.indices) {
        val v = bytes[j].toInt() and 0xFF // Here is the conversion
        hexChars[j * 2] = HEX_ARRAY[v.ushr(4)]
        hexChars[j * 2 + 1] = HEX_ARRAY[v and 0x0F]
    }

    return String(hexChars)
}

fun main(args: Array<String>) {
    val s = "hello_world"
    println(bytesToHex(s.toByteArray(Charset.forName("UTF-8"))))
}

If you run this you get on the console this:

68656C6C6F5F776F726C64