Returns true if this nullable collection is either null or empty. Returns an array of Short containing all of the elements of this collection. Returns an array of Double containing all of the elements of this collection. Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. and appends only the non-null results to the given destination. Appends all elements to the given destination collection. List.isEmpty() function returns true if the collection is empty (contains no elements), false otherwise. W3cubDocs / Kotlin W3cubTools Cheatsheets About. ... Returns true if the collection is not empty. In other words, it is an interval between a start and an end value. Returns a single list of all elements yielded from results of transform function being invoked on each element of original collection. Returns this Collection if it's not null and the empty list otherwise. Groups values returned by the valueTransform function applied to each element of the original collection In Part 3, I go over numbers and math in Kotlin. list.isEmpty() Return Value. Returns a list containing all elements that are instances of specified type parameter R. Returns a list containing all elements that are instances of specified class. A great example of this functionality is theCollection?.isNullOrEmptyfunction. to each element and current accumulator value that starts with initial value. Add a dependency code to your module's build.gradle file. Appends all elements not matching the given predicate to the given destination. By default, variables are non-null references and cannot be set to null. Returns the first element having the largest value according to the provided comparator or null if there are no elements. Returns a list containing all elements of the original collection and then all elements of the given elements collection. Returns true if at least one element matches the given predicate. snapshot is a list. Creates a Grouping source from a collection to be used later with one of group-and-fold operations Returns an array of UByte containing all of the elements of this collection. Applies the given transform function to each element and its index in the original collection Returns a list containing only the non-null results of applying the given transform function applied to each element and puts to the destination map each group key associated with a list of corresponding elements. to an each pair of two adjacent elements in this collection. Returns a new map containing all key-value pairs from the given collection of pairs. We'll now look at the different ways of creating ranges in Kotlin. Creating Collec­tions. Appends all elements yielded from results of transform function being invoked on each element and applies the given transform function to an each. If you need a Kotlin workshop, check how we can help you: kt.academy. to current accumulator value and each element with its index in the original collection. Creates a Sequence instance that wraps the original collection returning its elements when being iterated. The sheer number of different sorting functions can get confusing, so I’ve created the following table to summarize them: These functions all evaluate a predicate though all relevant elements and return a Boolean result. Returns a list containing first elements satisfying the given predicate. Checks if the specified element is contained in this collection. Here’s the link to the cheatsheet covering all 5 parts again. Returns a list of pairs built from the elements of this collection and the other array with the same index. Example 1: Check if List is Empty So this in Kotlin: val someList = people.filter { it.age <= 30 }.map { it.name } is the same as: Returns the largest value according to the provided comparator Returns true if the collection has no elements. Returns index of the first element matching the given predicate, or -1 if the collection does not contain such element. In this short article, we will discuss how to check if the collection is empty or null in Java. These are often useful as an exit condition for while loops or as a check for the base case in recursive functions. Returns a random element from this collection. Just as regular variables are non-null by default, a normal collection also can’t hold null values - val regularList: List = listOf(1, 2, null, 3) 1. internal. E - the type of elements contained in the collection. Returns an array of UInt containing all of the elements of this collection. A function is nothing but a collection of statements. Returns a set containing all distinct elements from both collections. Returns the first element having the smallest value according to the provided comparator or null if there are no elements. 1. isNullOrEmpty() function. Groups values returned by the valueTransform function applied to each element of the original collection It returns a single element, or null if the collection has more than one element or it is empty. Returns a list of snapshots of the window of the given size The Kotlin standard library offers a lot of functions for performing operations on collections. Here's how you can create a secondary constructor in Kotlin: to the end of the variable. In C#, IsNullOrEmpty() is a string method. using the specified random instance as the source of randomness. Check if Collection is Empty or Null in Java - Utility Methods. Returns the last element, or null if the collection is empty. among all values produced by selector function applied to each element in the collection. Returns a list containing all elements of the original collection except the elements contained in the given elements array. Returns a list containing all elements of the original collection except the elements contained in the given elements collection.