Padding string in Kotlin

Question

I was trying to pad a string in Kotlin to achieve some proper alignment on the console output. Something along these lines:

accountsLoopQuery                             - "$.contactPoints.contactPoints[?(@.contactAccount.id)]"
brokerPassword                                - *****
brokerURI                                     - tcp://localhost:61616
brokerUsername                                - admin
contactPointPriorityProperties                - "contactPointPriority.properties"
customerCollection                            - "customer"
customerHistoryCollection                     - "customer_history"
defaultSystemOwner                            - "TUIGROUP"

I have ended up coding it this way - cheating with Java's String.format:

mutableList.forEach { cp ->
    println(String.format("%-45s - %s", cp.name, cp.value))
}

Is there a proper way to do this with the Kotlin libraries?

Answer 1

You can use the .padEnd(length, padChar = ' ') extension from kotlin-stdlib for that. It accepts the desired length and an optional padChar (default is whitespace):

mutableList.forEach {
    println("${it.name.padEnd(45)} - ${it.value}")
}

There's also padStart that aligns the padding in the other direction.

Answer 2

You can using String#format extension function instead, In fact, it is inlined to call-site function with java.lang.String#format for example:

mutableList.forEach { cp ->
    println("%-45s - %s".format(cp.name, cp.value))
}