Introduction In this article, You’ll learn how to join two lists in kotlin programming language. Joining two lists or ArrayList can be done using List addAll () or apache commons ListUtils.union () method and show examples on each method. This method will use the natural order of the elements. A quick programming guide to join two lists in kotlin. Sort The simplest way to sort a collection is to call the sort method. So, it explains how the reassignment happens.įurther, let’s look at the implementation of List‘s ‘ +‘ ( plus operation) operator: public operator fun Collection. Kotlin provides multiple utilities to make the process of sorting collections easier. Now, let’s take a closer look at this compilation error. First, as the List interface and its super types don’t have the plusAssign() function, here, myList += “Tom Cruise” is the same as myList = myList + “Tom Cruise”. However, the error message is different this time: “ Kotlin: Val cannot be reassigned.” This means that the size of an ArrayList type can also increase or decrease dynamically.
An ArrayList type is a dynamic implementation of the array data type that allows you to add and remove element (s) from the array. Next, let’s test the += operator: val myList = listOf("Tom Hanks", "Brad Pitt")Īs we’ve expected, the code doesn’t compile either. The ArrayList class in Kotlin can be used to create a variable of ArrayList type. If we compile the code above, the compiler complains: “Kotlin: Unresolved reference: add.” This is expected, as the List interface doesn’t have the add() method. But let’s create a test to verify if it’s true: var myList = listOf("Tom Hanks", "Brad Pitt") Since List is read-only, we can’t add an element to it. Finally, let’s look at the List type in Kotlin.
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