Trailing lambda convention in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the function using the trailing lambda convention.

Kotlin

fun greet(action: () -> Unit) {
    action()
}

greet() [1] {
    println("Hello!")
}

Drag options to blanks, or click blank then click option'

A()

B() -> Unit

C() ->

D() -> {}

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the parentheses entirely when the function requires them.

Trying to put the lambda inside the parentheses incorrectly.

The trailing lambda convention allows you to pass the lambda outside the parentheses if it is the last argument. So you just call greet() followed by the lambda block.

2fill in blank

medium

Complete the code to define a function that takes a lambda and call it using trailing lambda syntax.

Kotlin

fun repeatAction(times: Int, action: () -> Unit) {
    for (i in 1..times) {
        action()
    }
}

repeatAction(3) [1] {
    println("Hi")
}

Drag options to blanks, or click blank then click option'

A()

B() -> Unit

C() ->

D{}

Attempts:

3 left

💡 Hint

Common Mistakes

Removing the parentheses entirely.

Putting the lambda inside the parentheses incorrectly.

When calling repeatAction, the lambda is the last argument, so you put it outside the parentheses. The parentheses must still be present for the first argument.

3fill in blank

hard

Fix the error in calling the function with trailing lambda syntax.

Kotlin

fun calculate(operation: (Int, Int) -> Int): Int {
    return operation(5, 3)
}

val result = calculate [1] { (a, b) -> a + b }
println(result)

Drag options to blanks, or click blank then click option'

A[

B(

C{

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of curly braces for the lambda.

Using square brackets or angle brackets.

The lambda expression must be enclosed in curly braces {} when used as a trailing lambda.

4fill in blank

hard

Fill both blanks to define and call a function using trailing lambda syntax correctly.

Kotlin

fun operate(x: Int, y: Int, operation: (Int, Int) -> Int): Int {
    return operation(x, y)
}

val sum = operate(4, 5[1] [2] a, b -> a + b)

Drag options to blanks, or click blank then click option'

A,

B)

C{

D]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a comma instead of closing parenthesis before the lambda.

Omitting the closing parenthesis before the trailing lambda.

Close the parentheses after the regular arguments with ')', then start the trailing lambda with '{' outside the parentheses.

5fill in blank

hard

Fill all three blanks to create a function call with trailing lambda and print the result.

Kotlin

fun transform(value: Int, operation: (Int) -> Int): Int {
    return operation(value)
}

val result = transform[1] 10[2] [3] x -> x * 2
println(result)

Drag options to blanks, or click blank then click option'

A(

B,

C{

D)

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the closing parenthesis before the trailing lambda.

Using a comma instead of ')' after the argument.

Open the parentheses with '(', pass the first argument '10', close with ')', then start the trailing lambda with '{' outside the parentheses.