What will be the output of this Kotlin code?

medium📝 Predict Output Q4 of 15

Kotlin - Collections Fundamentals

val list = mutableListOf(1, 2, 3)
list.add(4)
println(list)

A[1, 2, 3]

B[1, 2, 3, 4]

C[4, 1, 2, 3]

DCompilation error

Step-by-Step Solution

Solution:

Step 1: Understand mutableListOf() and add()
mutableListOf creates a mutable list; add(4) appends 4 to the list.
Step 2: Predict the printed list
After adding 4, the list contains [1, 2, 3, 4], so println outputs this.
Final Answer:
[1, 2, 3, 4] -> Option B
Quick Check:
Mutable list after add() = [1, 2, 3, 4] [OK]

Quick Trick: mutableListOf() allows add() to change list [OK]

Common Mistakes:

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