provided by transform function applied to each element of the given collection. Returns the largest value among all values produced by selector function str1 contains null value and str2 is an empty string. Returns the index of the last occurrence of the specified element in the list, or -1 if the specified to an each pair of two adjacent elements in this collection. Returns the last element matching the given predicate, or null if no such element was found. The returned list is serializable (JVM). Example 1: Check if List is Empty In this example, we will take an empty list, and check if it is empty or not programmatically. 3. mutableListOf() creates an empty list that can hold User objects. Returns a set containing all elements that are contained by this collection and not contained by the specified collection. Returns a single list of all elements yielded from results of transform function being invoked on each element The second thing to notice is that we need to guarantee that the caller gets a value. To use the is operator with the “smart cast” feature in a when block: As of Kotlin 1.4, it’s possible to break or continue a loop even inside a when expression. Cases in Kotlin can be dynamic expressions that are evaluated at runtime. Let's create an ArrayList class with initialize its initial capacity. In Kotlin we have a huge list of such functions but here we will share some of the most used functions. Returns a list iterator over the elements in this list (in proper sequence). Returns a list of all elements sorted descending according to natural sort order of the value returned by specified selector function. Returns true if the collection is not empty. Exploring ArrayList Functions. to current accumulator value and each element with its index in the original collection. If we omit the argument in the when block, then the case expressions should evaluate as either true or false. having distinct keys returned by the given selector function. Returns an array of Double containing all of the elements of this collection. Performs the given action on each element and returns the collection itself afterwards. Similar to the library, the list collection also stores the objects based on the index number, and it can also store duplicate objects as the access is going to happen through the index. Accumulates value starting with the last element and applying operation from right to left by the key returned by the given keySelector function applied to the element Returns the smallest value among all values produced by selector function This essentially means that no break statements are needed at the end of each case block. Returns true if collection has at least one element. Environment Kotlin 1.2.0 Empty Empty means no-content. Returns a list containing only elements matching the given predicate. Returns the index of the first occurrence of the specified element in the list, or -1 if the specified otherwise the result is undefined. Methods in this interface support only read-only access to the list; To initialize Kotlin List, use mutableListOf(vararg items : T) method. However, Kotlin provides us with a feature called “smart cast”. The method returns a MutableList.In the following example,each item is of type String andlistA is List listB is MutableList Appends the string from all the elements separated using separator and using the given prefix and postfix if supplied. Returns a list containing only the non-null results of applying the given transform function Returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this collection. Returns a list containing successive accumulation values generated by applying operation from left to right Returns a single list of all elements yielded from results of transform function being invoked on each element of original collection. So this is me coming back to see what I can do to make these classes better, if anything. Returns a list of all elements sorted according to the specified comparator. Returns the number of elements matching the given predicate. Returns an original collection containing all the non-null elements, throwing an IllegalArgumentException if there are any null elements. Let’s also define a hierarchy of classes that model the respective Unix file types: To check that the argument is in a range: We and our partners share information on your use of this website to help improve your experience. Kotlin List is an interface and generic collection of elements. Populates and returns the destination mutable map with key-value pairs, These are some important points you should know before working with Kotlin MutableList: List is read-only (immutable), you cannot add or update items in the original list. Splits the original collection into pair of lists, to current accumulator value and each element. Returns last index of element, or -1 if the list does not contain element. Returns a list containing the results of applying the given transform function Creates a Grouping source from a collection to be used later with one of group-and-fold operations In Kotlin, if a matching case is found then only the code in the respective case block is executed and execution continues with the next statement after the when block. Creates a string from all the elements separated using separator and using the given prefix and postfix if supplied. In Kotlin, you can use reverse() extension function to reverse an array... Another solution is to create an auxiliary array of same type and size as the original array. Returns a list containing first elements satisfying the given predicate. Appends all elements yielded from results of transform function being invoked on each element Appends all elements that are instances of specified type parameter R to the given destination. Returns this array if it's not empty You can have a look at the introduction to the Kotlin Language article on Baeldung to learn more about the language. Returns a list containing only the non-null results of applying the given transform function Returns an array of Long containing all of the elements of this collection. Checks if the specified element is contained in this collection. In this task, you change the score to a LiveData object in the ScoreViewModel and attach an observer to it. In Kotlin we can use find in order to return the first element matching the given predicate: val theFirstBatman = batmans.find { actor -> "Michael Keaton".equals (actor) } assertEquals (theFirstBatman, "Michael Keaton") However, if no such element is found the find will return null. Returns a list containing all elements except first elements that satisfy the given predicate. Accumulates value starting with initial value and applying operation from left to right where key is provided by the keySelector function and The is operator is similar to the instanceof operator in Java. equal to the provided key value using the binary search algorithm. To get a mutable list, you can use the toMutableList() function. A list is empty if and only if it contains no elements. using the specified random instance as the source of randomness. Performs the given action on each element, providing sequential index with the element, Accumulates value starting with the first element and applying operation from left to right Returns a random element from this collection using the specified source of randomness. snapshot is a list. Returns the single element, or throws an exception if the list is empty or has more than one element. To understand the material in this article, basic knowledge of the Kotlin language is needed. Applies the given transform function to each element and its index in the original collection Returns a new map containing all key-value pairs from the given collection of pairs. The first presentation I witnessed made it sound quite interesting, but the minute I decided to try it out, I truly fell in love with it. Checks if all elements in the specified collection are contained in this collection. Returns index of the first element matching the given predicate, or -1 if the list does not contain such element. 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