Use type inference judiciously declare explicit types for clarity and safety (to make sure you and the compiler are on the same page). In Kotlin, it appears the idiom is to use the built-in factory methods like mapOf and arrayOf when possible.ģ. Declarations should use generic types, like List and Map. Even with Java code, you shouldn't be declaring any variables as ArrayList or HashMap. As Stephan has already mentioned, avoid using specific implementations like HashMap and ArrayList. It seems to you have previously programmed in Java and have carried over some poor habits from working in Java.Ģ. Again, making Product immutable will require a shift in the way you're thinking about your program objects.

You might also be able to keep your Product data class immutable as well:ĭata class Product(val name: String, val availableQuantity: Int)Īlthough I'd have to see more details of how you're using it. This leads to non-functional code: var data: Map> That being said, I think I have a pretty decent handle on some of the Kotlin idioms. val associate = list.If you don't mind, a few comments on style.Ĭaveat: I've just recently started out with Kotlin myself so there may be better and more idiomatic ways than what I'm about to suggest below. So it makes it easier, associateBy is provided, with two lambdas, one of the key, the other for the value. data class Data(val firstName: String, val lastName: String) val list = listOf( Data('John', 'Ali'), Data('Naidu', 'Tan'), Data('Evgenii', 'Dmitry')) val associate = list. In a layman term, it is used to change a list into a map. Returns a Map containing key-value pairs provided by transform function applied to elements of the given array. To begin, let’s understand what is associate (if you already know, you could skip this section)

Let’s use associate as an example, as it has the complete set as shown above. However, if we could learn what is To, By and With refers to specifically, then it will make such learning much easier. associate, associateTo, associateBy, associateByTo, associateWith and associateWithTo. One good example that has it all is associate i.e. To add to the challenge, some of the functions have variants where the name is appended with To, By and With. Kotlin has lots of useful collection functions. Picture by Jaizer Capangpangan on Unsplash

Kotlin map for each