Overriding methods with override in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the override keyword do in Kotlin?

It tells the compiler that a method in a subclass is replacing a method with the same name and parameters in its superclass.

beginner

Why must you use override explicitly in Kotlin when overriding a method?

To avoid mistakes, Kotlin requires you to clearly say when you are changing a method from a parent class, making your code safer and easier to understand.

beginner

What happens if you try to override a method without using override in Kotlin?

The compiler will give an error because Kotlin wants you to be clear about overriding methods.

intermediate

Can you override a method that is not marked as open in Kotlin?

No, only methods marked with open or abstract methods can be overridden.

beginner

Show a simple example of overriding a method with override in Kotlin.

open class Animal {
    open fun sound() = "Some sound"
}

class Dog : Animal() {
    override fun sound() = "Bark"
}

fun main() {
    val dog = Dog()
    println(dog.sound()) // Output: Bark
}

What keyword must you use in Kotlin to override a method from a superclass?

A open

B super

C override

D extends

The override keyword is required to override a method in Kotlin.

Which keyword marks a method as overridable in Kotlin?

A open

B override

C final

D abstract

Methods must be marked open to be overridden, except abstract methods which are implicitly open.

What happens if you override a method but forget to use override keyword?

A The method overrides silently

B Warning only

C Runtime error

D Compiler error

Kotlin compiler requires override keyword and will show an error if it is missing.

Can you override a method marked as final in Kotlin?

A No

B Only if subclass is abstract

C Yes

D Only with <code>override</code>

Methods marked final cannot be overridden.

In Kotlin, what is the purpose of overriding a method?

A To add new methods to a class

B To change the behavior of an inherited method

C To delete a method from a class

D To create a new class

Overriding lets you change how a method works in a subclass.

Explain how and why you use the override keyword in Kotlin when working with classes.

Think about how Kotlin makes you clear when changing inherited methods.

Describe the relationship between open and override keywords in Kotlin.

One keyword allows change, the other confirms change.