I have declared below variables: val occupations = mapOf(Pair("Malcolm", "Captain"), Pair("Kaylee", "Mechanic")) val In this tutorial, we'll continue to learn the language by looking at the ranges and collections API in Kotlin. In the previous article in this series, you learned about nullability, loops, and conditions in Kotlin. Supported and developed by JetBrains Supported and developed by JetBrains ... As we can see, if we omit the prefix and suffix, they are the empty string, and if we omit the separator, then it is the string “, “. All these code examples which use "docSnapshot.exists" checking, arent they forgetting that this is not a transaction, so it can not guarantee that by the time the client find out that doc does not exist and it triggers a create new doc, someone else might have created that doc, in … internal. Returns true if the element is found in the collection. InlineOnly: public inline fun < T > Collection. * @sample samples.collections.Collections.Collections.collectionIsNotEmpty */ @kotlin. : run { // execute this block if null } But this seems not to be quite as readable as a simple if-else statement. Returns a list containing the non-null results of applying the given transform function to each element of the original collection. isNotEmpty (): Boolean = !isEmpty() /* * * Returns `true` if this nullable collection is either null or empty. Here, you added safe call operators. Also, you might find this Q&A useful: In Kotlin, what is the idiomatic way to deal with nullable values, referencing or converting them A quick and practical guide to collection processing in Kotlin. data?.let { // execute this block if not null } ? Kotlin is a modern programming language that compiles to Java bytecode.It is free and open source, and promises to make coding for Android even more fun. WhatIf ☔ Fluent expressions of Kotlin for handling single if-else statements, nullable, collections, and boolean. 3. [kotlin] assertEquals(listOf(2, 4, 6, 8), listWithNull mapNotNull { it * 2 }) [/kotlin] 18.4 Elements operations contains. Download ☔ WhatIf has been downloaded in more than 50k Kotlin and Android projects all over the world! In a way, the double exclamation mark is Kotlin yelling at you not to use it too often!! dropWhile is another filter that takes a predicate but dropWhile works from index 0 -> n and dropLastWhile works from index n -> 0. * Returns `true` if the collection is not empty. If we try to drop more elements than the collection contains, we’ll just be left with an empty List. We can also specify a limit to the number of elements to combine. Add a dependency code to your module's build.gradle file. Take Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. Gradle. 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