Nested class independence from outer in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a nested class inside Outer.

Kotlin

class Outer {
    class [1] {
        fun greet() = "Hello from Nested"
    }
}

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

ANested

BInner

COuterNested

DCompanion

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Inner' instead of 'Nested' which changes the class type.

Using 'Companion' which is for companion objects, not nested classes.

The keyword class Nested declares a nested class inside Outer. Nested classes do not have access to the outer class instance.

2fill in blank

medium

Complete the code to create an instance of the nested class.

Kotlin

val nested = Outer.[1]()

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

AInner

BCompanion

CNested

DOuterNested

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to create an instance of 'Inner' which requires an outer instance.

Using 'Companion' which is not a class.

To create an instance of a nested class, use Outer.Nested(). Nested classes do not require an outer instance.

3fill in blank

hard

Fix the error in accessing the outer class property from the nested class.

Kotlin

class Outer(val name: String) {
    class Nested {
        fun printName() = [1]
    }
}

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

Aname

B"Cannot access outer property"

[e-mail]

DOuter().name

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use '[e-mail]' inside a nested class which is invalid.

Creating a new Outer instance to access name which is not the same as the outer instance.

Nested classes do not have access to the outer class instance or its properties. So you cannot access name directly. The correct approach is to pass the value explicitly if needed.

4fill in blank

hard

Fill both blanks to create an inner class that can access the outer class property.

Kotlin

class Outer(val name: String) {
    inner class [1] {
        fun printName() = [2]
    }
}

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

AInner

BNested

[e-mail]

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Nested' instead of 'Inner' which does not allow access to outer properties.

Using just 'name' without 'this@Outer' which causes ambiguity.

Using inner class Inner allows access to the outer class instance. Inside the inner class, [e-mail] accesses the outer property.

5fill in blank

hard

Fill all three blanks to create a nested class with a function that returns a greeting including a passed outer class name.

Kotlin

class Outer {
    class [1] {
        fun greet(name: String) = "Hello, [2]!"
    }
}

val nested = Outer.[3]()
println(nested.greet("Alice"))

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

ANested

B$name

DInner

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Inner' instead of 'Nested' for the class name.

Using '\$name' instead of '$name' which prevents interpolation.

Trying to create an instance of 'Inner' without an outer instance.

The nested class is named 'Nested'. The greet function uses string interpolation with $name to include the passed name. The instance is created with Outer.Nested().