Convert a Long/ULong to an unsigned hexadecimal string with padding zeros

Question

How to convert a Long/ULong representing an unsigned long to an unsigned hexadecimal string with padding zeros (a 16-digit hexadecimal string)?

I am looking for a simple and neat solution in Kotlin or Java.

Answer 1

val mutableList = listOf(121212L, 121212121212L,-1L)
mutableList.forEach {
    println(it.toULong().toString(16).padStart(16, '0'))
}

it gives

000000000001d97c
0000001c38ce307c
ffffffffffffffff

Edited: Credit to Ilya in the comment for the missing toULong part.