The most common operation when you work with collections is iteration through collection items for (int i = 0 i friend.id = index Let’s check all important functions that we have in the llection framework and compare it to an implementation to Java. But if we compare it to Rx, there are no subscribers, observers, etc.

So the idea is that you have some stream of data, and using some functions you can receive some required state of the stream. This approach is very similar to Java 8 collections and Rx usage. Now I am going to show you the coolest thing in Kotlin collections – the functional approach Kotlin provides on top of collections. Thanks for reading! I’ll see you soon for Part 3, where I will cover List mapping.Software Engineer Android the two previous articles we talked about collections structure and all the possible ways to create them. I find people.isNotEmpty() a little easier to read, but any() certainly requires fewer keystrokes.Įxamples: people.any() // = true, the list is NOT empty noPeople.any() // = false, the list is empty any always return true when called on an empty list. Why use any() vs the other two? I don’t have a definitive answer for you.

Calling people.any() is equivalent to people.size > 0 or people.isNotEmpty(). The any() method can be used to check if a List contains at least one element. We created two lists here people has three Person elements, and noPeople has zero Person elements (it’s empty).

data class Person(val name:String, val age:Int) val people = listOf( Person('Zander', 78), Person('Fred', 12), Person('Ali', 35) ) val noPeople = emptyList() // empty list To explain how these methods work, let’s start with some sample data using Kotlin’s data class, as we did in Part 1.

Kotlin list find