Kotlin Functions Every Developer Should Know with Examples

Certainly! Here’s a collection of essential Kotlin functions that every developer should know, along with examples for each function:

let:

• Use let to execute a block of code on a non-null object.

val name: String? = "John" 
name?.let {
     println("Name is not null: $it") 
}

run:

• Use run to execute a block of code on an object, and it returns the result of the last expression.

val result = "Kotlin".run {
     println("The length is: $length")
     length * 2 
}

with:

• Use with to work with an object without the need to prefix each property or method with the object's name.

val person = Person("Alice", 30) with(person) {
     println("Name: $name, Age: $age") 
}

apply:

• Use apply to configure an object's properties and return the object itself.

val person = Person() person.apply {
     name = "Bob"     
     age = 25 
}

also:

• Use also to perform an additional action on an object and return the object itself.

val list = mutableListOf(1, 2, 3) 
val newList = list.also { it.add(4) }

takeIf:

• Use takeIf to check a condition on an object and return it if the condition is met, or null otherwise.

val number = 7 
val result = number.takeIf { it % 2 == 0 }

takeUnless:

• Similar to takeIf, but it returns the object if the condition is not met.

val number = 7 
val result = number.takeUnless { it % 2 == 0 }

map:

• Use map to transform elements in a collection and return a new collection with the transformed elements.

val numbers = listOf(1, 2, 3, 4, 5) 
val squared = numbers.map { it * it }

filter:

• Use filter to filter elements in a collection based on a condition and return a new collection with the filtered elements.

val numbers = listOf(1, 2, 3, 4, 5) 
val evenNumbers = numbers.filter { it % 2 == 0 }

reduce:

• Use reduce to perform a cumulative operation on the elements of a collection.

val numbers = listOf(1, 2, 3, 4, 5) 
val sum = numbers.reduce { acc, number -> acc + number }

forEach:

• Use forEach to iterate through the elements of a collection and perform an action on each element.

val fruits = listOf("apple", "banana", "cherry")
fruits.forEach { println("Fruit: $it") }

when expression:

• Use the when expression for conditional branching.

val grade = 85 val result = when {
     grade >= 90 -> "A"
     grade >= 80 -> "B"
     grade >= 70 -> "C"
     else -> "F" 
}

These are just a few essential Kotlin functions and features every developer should know. Kotlin offers a wide range of powerful functions and features that can help make your code more concise and expressive.

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