Question: Is there a quick way to split a String by fixed number of chars in Kotlin?

I need to split this `544A1609B62E`, lowercase it, add `:` where needed and achieve this: `54:4a:16:09:b6:2e`.

What would be the idiomatic way to do it?

Answer: 
In Kotlin 1.2 you can do this:

```
"544A1609B62E".toLowerCase().chunked(2).joinToString(":")

```

The `chunked` function is new in Kotlin 1.2. It splits a collection into chunks of the given size.

Doing this in Kotlin 1.1 or lower is a bit more cumbersome. You could look at the answers in the question posted by @NSimon here: [Java: How to split a string by a number of characters?](https://stackoverflow.com/questions/9276639/java-how-to-split-a-string-by-a-number-of-characters)
Another try in Kotlin,

```
val sampleString = "544A1609B62E"
        var i = 0
        var sampleBuffer = "";
        while(i < sampleString.length - 2) {
            sampleBuffer = sampleBuffer.plus(sampleString.toLowerCase ().substring(i, i + 2)).plus(":")
            i += 2
        }

        sampleBuffer = sampleBuffer.plus(sampleString.toLowerCase().substring(i))
        Log.e(TAG, sampleBuffer)

```