[Solved] What will be the output of this Kotlin code? val list: List = listOf(1, 2, 3) // list.add(4) // Uncommenting this line println(list) | Kotlin

Kotlin - Collections Fundamentals

What will be the output of this Kotlin code?

val list: List = listOf(1, 2, 3)
// list.add(4) // Uncommenting this line
println(list)

A[1, 2, 3]

BCompilation error due to add() on immutable List

C[1, 2, 3, 4]

DRuntime exception when calling add()

Step-by-Step Solution

Solution:

Step 1: Understand List interface mutability
List is immutable and does not have add() method, so calling add() causes a compile error.
Step 2: Analyze code behavior
Uncommenting list.add(4) will cause compilation failure, so no output is produced.
Final Answer:
Compilation error due to add() on immutable List -> Option B
Quick Check:
Immutable List disallows add() [OK]

Quick Trick: Immutable List has no add() method; causes compile error [OK]

Common Mistakes:

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