Trailing lambda convention in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the trailing lambda convention in Kotlin?

It is a Kotlin syntax feature that allows you to pass a lambda expression outside the parentheses of a function call if the lambda is the last argument.

beginner

How do you call a function with a trailing lambda in Kotlin?

You write the lambda expression after the function call parentheses instead of inside them, making the code cleaner and more readable.

beginner

Example: Convert this call to use trailing lambda:

list.filter({ it > 5 })

list.filter { it > 5 }

The lambda is moved outside the parentheses because it is the last argument.

intermediate

Can you use trailing lambda if the lambda is not the last argument?

No, trailing lambda syntax only works if the lambda is the last argument in the function call.

beginner

Why is trailing lambda convention useful?

It makes code easier to read and write, especially when lambdas are long or nested, by reducing parentheses clutter.

What does the trailing lambda convention allow in Kotlin?

A Calling functions without parentheses

B Using lambdas only inside parentheses

C Defining lambdas without curly braces

D Passing a lambda expression outside the parentheses if it is the last argument

Trailing lambda lets you put the lambda outside the parentheses when it is the last argument.

Which of these is a correct use of trailing lambda?

A list.map { it * 2 }

B list.map({ it * 2 })

C list.map it * 2

D list.map it => it * 2

Option A uses trailing lambda syntax correctly by placing the lambda outside parentheses.

Can you use trailing lambda if the function has multiple arguments and the lambda is not last?

A Yes, always

B No, only if lambda is last argument

C Only if lambda is first argument

D Only if function has one argument

Trailing lambda works only when the lambda is the last argument.

What is a benefit of using trailing lambda?

A Makes code more readable and less cluttered

B Makes code run faster

C Allows lambdas without curly braces

D Removes need for function names

Trailing lambda improves readability by reducing parentheses clutter.

Which Kotlin feature is demonstrated by this code?

button.setOnClickListener { println("Clicked") }

A Extension function

B Data class

C Trailing lambda convention

D Object declaration

The lambda passed outside parentheses shows trailing lambda convention.

Explain the trailing lambda convention in Kotlin and when you can use it.

Think about how lambdas are passed to functions.

Give an example of a function call using trailing lambda and explain why it is valid.

Try using list.filter or similar function.