Throw as an expression in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean that 'throw' is an expression in Kotlin?

In Kotlin, 'throw' can be used as an expression, meaning it can be part of other expressions like assignments or return statements, not just a standalone statement.

intermediate

How can you use 'throw' in an assignment in Kotlin?

You can assign a value or throw an exception in one line, for example: val x = someValue ?: throw IllegalArgumentException("Value required")

intermediate

Why is 'throw' being an expression useful in Kotlin?

It allows more concise and readable code by combining error handling with expressions, reducing the need for separate if-else blocks.

beginner

Can 'throw' be used inside a return statement in Kotlin?

Yes, you can write return throw Exception("Error") because 'throw' is an expression that never returns normally.

advanced

What type does the 'throw' expression have in Kotlin?

'throw' has the special type 'Nothing' in Kotlin, which means it never returns normally and can be used anywhere a value is expected.

In Kotlin, what type does the 'throw' expression have?

A Nothing

B Unit

C Any

D Void

'throw' has the type 'Nothing' which means it never returns normally and can be used as an expression anywhere.

Which of the following is a valid use of 'throw' as an expression in Kotlin?

A val x = value ?: throw IllegalArgumentException("Missing")

B throw IllegalArgumentException("Missing") val x = 5

C val x = throw IllegalArgumentException("Missing") ?: 5

D throw is only a statement, not an expression

Option A correctly uses 'throw' as an expression in the Elvis operator to throw an exception if value is null.

Why can 'throw' be used in places where a value is expected?

A Because Kotlin treats 'throw' as a function

B Because 'throw' returns a default value

C Because 'throw' has the type 'Nothing' which fits anywhere

D Because 'throw' is ignored by the compiler

'throw' has the special type 'Nothing' which means it never returns normally and can be used wherever a value is expected.

Which statement about 'throw' in Kotlin is true?

A 'throw' can only be used as a standalone statement

B 'throw' returns a Boolean value

C 'throw' is deprecated in Kotlin

D 'throw' can be used as an expression in assignments and returns

'throw' can be used as an expression, for example in assignments or return statements.

What benefit does 'throw' as an expression provide in Kotlin?

A It makes code longer and more complex

B It allows combining error handling with expressions for concise code

C It disables exception handling

D It forces all exceptions to be checked

'throw' as an expression lets you write shorter, clearer code by combining error handling with expressions.

Explain how 'throw' being an expression changes the way you write Kotlin code.

Think about how you can combine throwing exceptions with other expressions.

Describe the type of 'throw' in Kotlin and why it allows 'throw' to be used anywhere a value is expected.

Consider what 'Nothing' means in Kotlin's type system.