Kotlin emptyList Function | Create an Empty List in Kotlin

The emptyList function in Kotlin is used to create an empty, read-only list. This function belongs to the Kotlin standard library and provides a straightforward way to create an immutable list with no elements.

Table of Contents

1. Introduction
2. emptyList Function Syntax
3. Examples
   • Basic Usage
   • Using emptyList with Generic Types
   • Checking if a List is Empty
4. Real-World Use Case
5. Conclusion

Introduction

The emptyList function is a convenient way to create an empty, immutable list. This is useful for initializing lists, especially when you need to return an empty list from a function or when working with APIs that expect a list.

This list is type-safe, meaning you can specify the type of elements the list would contain if it were not empty.

emptyList Function Syntax

The syntax for the emptyList function is as follows:

fun <T> emptyList(): List<T>

Parameters:

• This function does not take any parameters.

Returns:

• An empty, read-only list of type T.

Examples

Basic Usage

To demonstrate the basic usage of emptyList, we will create an empty list and print its contents.

Example

fun main() {
    val emptyList = emptyList<Int>()
    println("Empty list: $emptyList")
}

Output:

Empty list: []

Using emptyList with Generic Types

This example shows how to use emptyList with different generic types.

Example

fun main() {
    val emptyStringList = emptyList<String>()
    val emptyIntList = emptyList<Int>()

    println("Empty string list: $emptyStringList")
    println("Empty integer list: $emptyIntList")
}

Output:

Empty string list: []
Empty integer list: []

Checking if a List is Empty

This example demonstrates how to check if a list is empty using the emptyList function.

Example

fun main() {
    val list = emptyList<Double>()

    if (list.isEmpty()) {
        println("The list is empty.")
    } else {
        println("The list is not empty.")
    }
}

Output:

The list is empty.

Real-World Use Case

Returning an Empty List from a Function

In real-world applications, the emptyList function can be used to return an empty list from a function, especially when there are no elements to return.

Example

fun getNumbers(condition: Boolean): List<Int> {
    return if (condition) {
        listOf(1, 2, 3)
    } else {
        emptyList()
    }
}

fun main() {
    val numbers = getNumbers(false)
    println("Numbers: $numbers")
}

Output:

Numbers: []

Conclusion

The emptyList function in Kotlin is a useful method for creating empty, immutable lists. It provides a simple way to initialize lists, return empty lists from functions, and work with APIs that expect lists. By understanding and using the emptyList function, you can effectively manage empty lists in your Kotlin applications.