[Tiny] Nice Way to Build Strings in Kotlin

One nice way to build a String in Kotlin is the buildString() top-level function. It takes a lambda as an argument, and within that lambda, you can use various append methods on a StringBuilder instance to construct a string.

Once the lambda is executed, the resulting StringBuilder object is converted to a regular String object.

Here is a sample:

private const val AGE_LENGTH = 4
private const val NAME_LENGTH = 14
private const val TABLE_LENGTH = 40

data class Person(val name: String, val age: Int, val motherland: String)

fun generateReport(people: List<Person>) = buildString {
    appendLine("Report:")
    appendLine("".padEnd(TABLE_LENGTH, '-'))

    appendLine("${"Name".padEnd(NAME_LENGTH)} | ${"Age".padEnd(AGE_LENGTH)} | Motherland")
    appendLine("".padEnd(TABLE_LENGTH, '-'))

    people.forEach {
        appendLine("${it.name.padEnd(NAME_LENGTH)} | ${it.age.toString().padEnd(AGE_LENGTH)} | ${it.motherland}")
    }
    appendLine("".padEnd(TABLE_LENGTH, '-'))
}

fun main() {
    val people = listOf(
        Person("Frodo Baggins", 33, "The Shire"),
        Person("Gandalf", 2019, "Middle-earth"),
        Person("Aragorn", 87, "Gondor"),
        Person("Legolas", 2931, "Woodland Realm"),
        Person("Gimli", 139, "Lonely Mountain"),
    )

    val report = generateReport(people)
    println(report)
}

The output of the above code will be:

Report:
----------------------------------------
Name           | Age  | Motherland
----------------------------------------
Frodo Baggins  | 33   | The Shire
Gandalf        | 2019 | Middle-earth
Aragorn        | 87   | Gondor
Legolas        | 2931 | Woodland Realm
Gimli          | 139  | Lonely Mountain
----------------------------------------

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