I hope the above gives a bit of an insight into different ways of looping in Kotlin. This shouldn’t matter much in terms of performance, but it’s something to be aware of in performance critical code. In a nutshell, the Kotlin compiler creates an Iterable object and IntRange object, and then the iteration will take place. While the Kotlin forEach on a range looks pretty similar to the other options, under the hood things work a bit different, which can be seen in the linked video at the 25-minute mark. As such, the syntax of for loop in Kotlin is: for (element in collection) Kotlin loop using a forEach Any class which provides an iterator can be looped over. In Kotlin the for loop is used to iterate through a diversity of types to loop over, such as collections, ranges and maps. Inspired by the Kotlin Under the Hood: Understand the Internals (Google I/O’19) video (which is a really good video btw, I’d recommend watching it if you haven’t), I wanted to list a few ways of looping it Kotlin.

Kotlin provides its own way of looping on ranges. IntStream.range(0, 100).forEach(System.out::println) A Kotlin Approach

For instance, heres a way to create a range of numbers from. Examples of either can be seen below: // Traditional for loop Kotlin raises the level of abstraction to iterate over a range of values with specialized classes. A more modern approach would be something like using a Java 8 IntStream. One of the most well-known ways to iterate on a range is to use the traditional for loop. There’s a common way in Java to do loops.

For loop kotlin range