Swift if Let Statement Equivalent in Kotlin

1. Compare Swift if let Statement and Kotlin let and run Functions
2. Use the let and run Functions as Swift if let Statement Equivalent in Kotlin

Swift if let statements allow combining if and null checking statements into a single code block. It helps eliminate all the -nil pointer exceptional bugs by checking if the value of a variable or constant is null.

What if we want to use the same thing in Kotlin? In Kotlin, we can use let and run or the Elvis operator (? :) as equivalent to the Swift if let statement.

This article will demonstrate the let and run functions as Swift if let statement equivalent in Kotlin.

Compare Swift if let Statement and Kotlin let and run Functions

Here is how we can use the Swift if let statement.

if let x = y.val {

} else {

}

Syntax for the let and run functions:

val x = y?.let {
    // enter if y is not null.
} ?: run {
    // enter if y is null.
}

In the syntax above, we need to use the run block of code only if we have multiple lines of code after the Elvis operator. We can skip the run block if there is only a single line of code post the Elvis operator.

Also, when using the Kotlin let and run, the compiler cannot access the variable from within the let and run blocks. Since the Kotlin Elvis operator is a nil-checker, the run code will only execute if y is null or if the let block evaluates to null.

Use the let and run Functions as Swift if let Statement Equivalent in Kotlin

Let us look at an example to understand how to implement Kotlin let and run functions in a program. This example will check the variable’s value.

The compiler will execute the let block if it is null; otherwise, it will perform the run block.

Example 1:

fun main(args: Array<String>) {

    val y="Hello"
    val x = y?.let {
        // This code runs if y is not null
        println("Code A");
    } ?: run {
        // This code runs if y is null
        println("Code B");
    }
}

Output:

The output runs the let code since the value of y is not null.

Now, let’s try by making the value of y null.

Example 2:

fun main(args: Array<String>) {

    val y= null
    val x = y?.let {
        // This code runs if y is not null
        println("Code A");
    } ?: run {
        // This code runs if y is null
        println("Code B");
    }
}

Output: