Hello, I am using `joinToString(", ")` to construc...

# announcements

[Marcin Wisniowski]

Hello, I am using joinToString(", ") to construct a comma separated string from a list of names. What would be an idiomatic way to make the last comma an "and" instead? I am getting "a, b, c, d", but want to get "a, b, c and d". I can replace it afterwards, or join all the names except the last one and add it separately, but maybe someone here has an elegant solution I'm not seeing?

This is the best I can currently think of:
names.dropLast(1).joinToString(", ") + " and " + names.last()

[gildor]

No elegant solution, just use if condition for those 2 cases

[gildor]

if (names.size < 2) {
   names.firstOrNull() ?: ""
} else {
  names.dropLast(1).joinToString(", ") + " and " + names.last()
}

[gildor]

it would be elegant enough if extract it to own extension function

[Marcin Wisniowski]

That's pretty much the if statement I have, except I use singleOrNull() instead of firstOrNull(). Good idea with just moving that to an extension function, I will do that.

[Marcin Wisniowski]

fun List<String>.joinToString(separator: String, lastSeparator: String): String {
    return if (size > 1) {
        dropLast(1).joinToString(separator) + lastSeparator + last()
    } else {
        singleOrNull() ?: ""
    }
}

I'm happy with this. 🙂