private val hexArray = CharArray(16) { if (it < 10) '0' + it else 'a' + (it - 10) }
fun ByteArray.toHexString(): String {
    val builder = StringBuilder(size * 2)
    for (byte in this) {
        val v = byte.toInt() and 0xFF
        builder.append(hexArray[v.ushr(4)])
        builder.append(hexArray[v and 0x0F])
    }
    return builder.toString()
}

BigInteger

byteArrayFromHexString()

ByteArray

private val CHARS = "0123456789ABCDEF".toList().toCharArray()

fun Byte.toHex() = toInt().let { "${CHARS[it.shr(4).and(0x0F)]}${CHARS[it.and(0x0F)]}" }

fun List<Byte>.toHexString(sep: String = "") = map(Byte::toHex).joinToString(separator = sep)


fun String.hexList(): List<Byte> = with(filter { it != ':' }.toUpperCase()) {
    if (length % 2 != 0) throw NumberFormatException("Odd number of characters: $length")
    if (!all { it in CHARS }) throw NumberFormatException("Invalid characters: ${this@hexList}")
    ByteArray(length / 2).mapIndexed { i, _ ->
        ((CHARS.indexOf(this[i * 2]).shl(4)) + (CHARS.indexOf(this[i * 2 + 1]))).toByte()
    }
}

fun ByteArray.toHexString(sep: String = "") = toList().toHexString(sep)

Companion

CharArray

ByteArray

List<Byte>

WeakReference

Comparator

List

typealias myproject.Random = java.util.Random

myproject.Random