Convert a nullable Int (Int?) to an Int in Kotlin

This article explores different ways to convert a nullable Int (Int?) to an Int in Kotlin.

1. Using `!!` operator

The not-null assertion operator (!!) asserts that the receiver expression is not equal to null. It converts any value to a non-null type and throws NullPointerException if the value is null. You can use it to convert an Int? to an Int, as shown below:

fun main() {

val nullableInt: Int? = 10

val notNullableInt: Int = nullableInt!!

print(notNullableInt)

}

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2. Using Elvis Operator

Instead of throwing a NullPointerException when the value is null, you can return a default value with an Elvis operator (?:). If the expression to the left of ?: is not null, the Elvis operator returns it; otherwise, it returns the expression to the right.

fun main() {

val nullableInt: Int? = null

val notNullableInt: Int = nullableInt ?: 0

print(notNullableInt)

}

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3. Performing Null Check

Alternatively, you can perform an explicit null check on the Int? value and assign a default value when the value is null.

fun main() {

val nullableInt: Int? = null

var notNullableInt: Int = 0 // default value

if (nullableInt != null) {

notNullableInt = nullableInt

}

print(notNullableInt)

}

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You can also throw NPE if the value is null.

fun main() {

val nullableInt: Int? = 10

if (nullableInt != null)

{

val notNullableInt: Int = nullableInt

print(notNullableInt)

}

else {

throw NullPointerException()

}

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That’s all about converting a nullable Int to an Int in Kotlin.

Convert a nullable Int (Int?) to an Int in Kotlin

1. Using !! operator

2. Using Elvis Operator

3. Performing Null Check

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1. Using `!!` operator