How to merge two collections

In this recipe, we will see how to merge two or more collections into one. However, before we move ahead, we need to understand the difference between mutable and immutable types. An immutable type object is an object that cannot be changed. For example, if we define an immutable list, we won't be able to add other objects to it. With that in mind, let's start the recipe!

Getting ready

I'll be using IntelliJ IDEA for coding. You can use whichever IDE you like as long as it is able to compile and run Kotlin code.

How to do it…

You can create a list in Kotlin with the listOf method. However, the list returned by this method is an immutable list, so we need to create a mutable list in order to add objects to it. Let's check out the mentioned steps:

1. Let's create two lists, listA and listB, as follows:

var listA= mutableListOf<String>("a","a","b")
var listB= mutableListOf<String>("a","c")

Note

If the type declaration is inferred from the objects inside the listOf...