Recap - Library Card

Part of the Object Oriented Programming section of Coddy's Kotlin journey. Lesson 6 of 57.

Challenge

Medium

Declare the class LibraryCard(val name: String, val limit: Int = 3). Its init block requires a non-blank name (name is empty) and a limit of at least 1 (limit must be positive). It keeps a list of borrowed titles. borrow(title) returns true and adds the title unless the card is at its limit or already holds it. giveBack(title) returns true when it removed the title. status() returns Ada: 2/3 (Dune, Emma) in borrowing order, or Ada: 0/3 when nothing is borrowed.

The supplied code reads the name, the limit (or an empty line for the default) and then commands +title or -title. It prints ok or no for each command and finally status(); an invalid card prints the error message instead.

Your code goes in LibraryCard.kt. Main.kt holds the supplied input/output code and cannot be edited.

Try it yourself

fun main() {
    // Supplied input/output code: keep it as it is
    val input = generateSequence(::readLine).toList()
    try {
        val card = if (input[1].isEmpty()) LibraryCard(input[0]) else LibraryCard(input[0], input[1].toInt())
        for (cmd in input.drop(2)) {
            val title = cmd.drop(1)
            val done = if (cmd.startsWith("+")) card.borrow(title) else card.giveBack(title)
            println(if (done) "ok" else "no")
        }
        println(card.status())
    } catch (e: IllegalArgumentException) {
        println(e.message)
    }
}