[Solved] You have a map val scores = mapOf("Alice" to 90, "Bob" to 85) and a list val bonuses = listOf(5, 10).... Which code correctly does this? | Kotlin

Kotlin - Collections Fundamentals

You have a map val scores = mapOf("Alice" to 90, "Bob" to 85) and a list val bonuses = listOf(5, 10). You want to safely get Bob's score and the bonus at index 2, returning 0 if missing, then sum them. Which code correctly does this?

Aval total = (scores["Bob"] ?: 0) + (bonuses.getOrNull(2) ?: 0)

Bval total = (scores.getOrNull("Bob") ?: 0) + (bonuses.getOrNull(2) ?: 0)

Cval total = (scores["Bob"] ?: 0) + (bonuses[2] ?: 0)

Dval total = (scores["Bob"] ?: 0) + bonuses.get(2)

Step-by-Step Solution

Solution:

Step 1: Access map value safely
scores["Bob"] ?: 0 safely gets Bob's score or 0 if missing.
Step 2: Access list element safely
bonuses.getOrNull(2) ?: 0 safely gets bonus at index 2 or 0 if out of bounds.
Step 3: Sum the two values
Adding these two safe values gives the total without errors.
Final Answer:
val total = (scores["Bob"] ?: 0) + (bonuses.getOrNull(2) ?: 0) -> Option A
Quick Check:
Safe map + safe list access with ?: for default [OK]

Quick Trick: Use ?: with map and getOrNull for list to avoid errors [OK]

Common Mistakes:

MISTAKES

Using bonuses[2] which throws exception if index invalid
Using getOrNull on map which is invalid
Not providing default fallback

Master "Collections Fundamentals" in Kotlin

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

More Kotlin Quizzes

Which code correctly does this?

Step 1: Access map value safely

Step 2: Access list element safely

Step 3: Sum the two values

Final Answer:

Quick Check:

Want More Practice?