Last element in list: Kotlin Is list empty: false Sublist from index 1 to 3 [Study, tonight] Kotlin Mutable List. It is a modifiable collection. In Kotlin, mutableListOf() method is used to instantiate MutableList Interface. I came up with following solution: when { activities != null && !activities.empty -> doSomething else -> doSomethingElse } Is there a more idiomatic way to do this in Kotlin? From the documentation of sort: Sorts the array in-place according to the natural order of its elements. */ @SinceKotlin(" 1.4 ") As frogcoder states in a comment, emptyList() does the same, but naturally returns an empty list. It inherits form Collection class. If you need an immutable empty list instance, you can use listOf() function as shown below. The MutableList interface also inherits the Collection interface. There are several ways to initialize an empty list as discussed below: 1. listOf() function. ArrayList is a mutable collection. Mutable lists (MutableList) Mutable lists can have elements added or removed. A key is a unique identifier for the value. List: listOf; Map: mapOf; Set: setOf; And mutable collections. Mutable lists are created using MutableList interface. Edit Page Constructing Collections Constructing from elements. https://www.baeldung.com/kotlin/initialize-empty-mutable-collections Contribute to JetBrains/kotlin development by creating an account on GitHub. It creates a MutableList implementation which provides a dynamic array size as its backing storage. Kotlin MutableList (mutableListOf()) Kotlin MutableList is an interface and generic collection of elements. If you don't want to sort the elements in-place but rather return a sorted list (your base doesn't need to be a MutableList), you can use sorted, sortedBy etc: The method mutableListOf() returns an instance of MutableList Interface and takes the array of a particular type or mixed (depends on the type of MutableList instance) elements or it can be null also. This creates an immutable list, similar to Arrays.asList in Java. Returns a new MutableMap with the specified contents, given as a list of pairs where the first component is the key and the second is the value.. MutableList interface is mutable in nature. MutableList class is used to create mutable lists in which the elements can be added or removed. all sort the items in the list itself. listOfNotNull() returns an immutable list excluding all null elements. This article explores different ways to initialize an empty List in Kotlin. ... * Removes the first element from this mutable list and returns that removed element, or throws [NoSuchElementException] if this list is empty. If the list is not null and not empty, I want to do something, otherwise I want to do something else. Mutable lists are dynamic in nature. Entries of the map are iterated in the order they were specified. We have two types of collections in Kotlin. The most common way to create a collection is with the standard library functions listOf(), setOf(), mutableListOf(), mutableSetOf().If you provide a comma-separated list of collection elements as arguments, the compiler detects the element type automatically. The methods of MutableList interface supports both read and write functionalities. It holds the data as key and value. The kotlin functions sort, sortBy etc. ... or returns `null` if this list is empty. 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