Kotlin Standard Library - Common Functions and Utilities

The Kotlin Standard Library is a rich set of functions and utilities that come bundled with Kotlin. It provides a wide range of tools to simplify common programming tasks and enhance productivity. In this guide, we'll explore some of the most commonly used functions and utilities from the Kotlin Standard Library.

Working with Collections

Kotlin's Standard Library includes powerful functions for working with collections, such as lists, sets, and maps. Some of the most commonly used functions include:

val numbers = listOf(1, 2, 3, 4, 5)
// Filtering
val evenNumbers = numbers.filter { it % 2 == 0 }
// Mapping
val squaredNumbers = numbers.map { it * it }
// Reducing
val sum = numbers.reduce { acc, num -> acc + num }

String Manipulation

You can perform various string manipulations using the Kotlin Standard Library:

val text = "Kotlin is a great language"
// Splitting
val words = text.split(" ")
// Joining
val joinedText = words.joinToString(" ")
// Formatting
val formattedText = text.capitalize()

File I/O

Kotlin provides utilities for working with files and directories:

import java.io.File
// Reading a text file
val file = File("example.txt")
val content = file.readText()
// Writing to a file
val outputFile = File("output.txt")
outputFile.writeText("Hello, Kotlin!")

Nullable Types and Safety

The Kotlin Standard Library offers functions and utilities to handle nullable types safely:

val nullableValue: Int? = null
// Safe call operator
val length = nullableValue?.toString()?.length
// Elvis operator
val result = nullableValue ?: 42

Date and Time Functions

Kotlin includes functions for working with dates and times:

import java.time.LocalDate
val currentDate = LocalDate.now()
val futureDate = currentDate.plusDays(7)


The Kotlin Standard Library is a valuable resource for Kotlin developers. It provides a wide array of functions and utilities that simplify common programming tasks and improve code quality. Whether you're working with collections, strings, files, or other aspects of your Kotlin applications, the Standard Library is there to help you write clean and efficient code.

Happy coding!