Properties with val and var in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the difference between val and var in Kotlin properties?

val declares a read-only property (like a constant). You cannot change its value after initialization. var declares a mutable property, which means you can change its value later.

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Can a val property be assigned a value after the object is created?

No. A val property must be assigned once during initialization and cannot be reassigned later.

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How do you declare a mutable property named age of type Int in Kotlin?

You declare it using var age: Int. This means you can change the value of age anytime.

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What happens if you try to reassign a val property in Kotlin?

The compiler will give an error because val properties are read-only and cannot be reassigned after initialization.

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Example: What will this code print?<br>

val name = "Anna"
// name = "Bob" // What if uncommented?

The code will print nothing because it only declares name. If you uncomment the reassignment, the compiler will show an error because name is a val and cannot be changed.

Which keyword declares a property that can be changed after initialization?

A var

B val

C const

D let

var declares a mutable property that can be reassigned. val is read-only.

What happens if you try to assign a new value to a val property?

A It works fine

B Value silently changes

C Runtime error

D Compiler error

The Kotlin compiler prevents reassignment of val properties, causing a compile-time error.

How do you declare a read-only property in Kotlin?

A val

B var

C let

D const

val declares a read-only property that cannot be reassigned.

Which of these is true about var properties?

A They cannot be changed after initialization

B They must be initialized with a value

C They can be reassigned any number of times

D They are constants

var properties are mutable and can be reassigned multiple times.

If you want a property that never changes after creation, which keyword do you use?

A var

B val

C mutable

D final

val creates a read-only property that cannot be changed after initialization.

Explain the difference between val and var properties in Kotlin with examples.

Think about constants versus variables in everyday life.

What error do you get if you try to change a val property after it is set? Why does Kotlin enforce this?

Consider why some things in life should not change once set.