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Pelajari alur filter, map, dan collect untuk mengolah data Java dengan kode yang mudah dibaca.
In Kotlin, you can combine multiple collection operations by chaining functions like filter, map, sortedBy, take, groupBy, and others. Each operation returns a new collection, so you can call the next operation directly on the result. val numbers = listOf(1, 2, 3, 4, 5, 6) val result = numbers .filter { it % 2 == […]
In Kotlin, destructuring lets you unpack values from an object into separate variables. It is commonly used with: Pair Map.Entry loops over maps lambda parameters Destructuring a Pair A Pair<A, B> contains two values: first and second. val pair = "Alice" to 25 val (name, age) = pair println(name) // Alice println(age) // 25 This […]
In Kotlin, associateBy, partition, and zip are collection operations that help transform or split collections. associateBy associateBy creates a Map from a collection by choosing a key for each element. data class User(val id: Int, val name: String) val users = listOf( User(1, "Alice"), User(2, "Bob"), User(3, "Charlie") ) val usersById = users.associateBy { user […]
In Kotlin, you can group elements with groupBy, then count how many items are in each group. Basic example val words = listOf("apple", "banana", "apricot", "blueberry", "avocado") val countsByFirstLetter = words .groupBy { it.first() } .mapValues { (_, words) -> words.count() } println(countsByFirstLetter) Output: {a=3, b=2} Here: groupBy { it.first() } groups words by their […]
In Kotlin, flatMap is used to transform each element into a collection and then flatten the results into a single list. Basic idea val result = items.flatMap { item -> // return a collection for each item } It is similar to: items.map { … }.flatten() but more concise. Example: flatten nested lists val nested […]
In Kotlin collections: map transforms each element into a new value. filter keeps only elements that match a condition. forEach performs an action for each element. map: transform elements Use map when you want to create a new collection by changing each item. val numbers = listOf(1, 2, 3, 4) val doubled = numbers.map { […]
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