Check out example codes for "format string kotlin android". It will help you in understanding the concepts better.

Code Example 1

// extend Long with a suitable function
fun Long.toFormattedString(format: String): String {
    // get the Long as String in order to be able to iterate it
    val s = this.toString()
    // provide a variable for the index
    var i = 0
    // create an empty result String
    var sb: String = ""

    // go through the pattern String
    for (c in format) {
        // replace # with the current cipher
        if (c == '#') {
            sb += s.get(i)
            // increment the counter
            i++
        } else {
            // for every other char in the pattern, just add that char
            sb += c
        }
    }

    return sb
}

// try it in a main function
fun main() {
    // provide an input and a pattern
    val l: Long = 110119225603
    val p = "##:##:## ##:##:##"
    // print the result of the extension function
    print(l.toFormattedString(p))
}

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