Kotlin - Collections Fundamentals
You want to create a map that stores student names as keys and their scores as values. You also want to update scores later. Which Kotlin code snippet correctly achieves this?
You want to create a map that stores student names as keys and their scores as values. You also want to update scores later. Which Kotlin code snippet correctly achieves this?
hard📝 Application Q15 of 15
Step-by-Step Solution
Solution:
Step 1: Choose a mutable map to allow updates
Since scores need to be updated,mutableMapOfis required.Step 2: Use correct method to update value
Assigning withscores["Alice"] = 95correctly updates the value in a mutable map.Step 3: Check other options for errors
val scores = mapOf("Alice" to 90, "Bob" to 85) scores["Alice"] = 95 uses immutable map and tries to update, causing error. val scores = mapOf("Alice" to 90, "Bob" to 85) scores.put("Alice", 95) tries to useputon immutable map, error. val scores = mutableMapOf("Alice" to 90, "Bob" to 85) scores.add("Alice", 95) uses non-existentaddmethod.Final Answer:
val scores = mutableMapOf("Alice" to 90, "Bob" to 85) scores["Alice"] = 95 -> Option DQuick Check:
mutableMapOf + assignment updates map [OK]
Quick Trick: Use mutableMapOf and bracket assignment to update entries [OK]
Common Mistakes:
MISTAKES- Using mapOf when updates are needed
- Trying to use put on immutable map
- Using add method which does not exist
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