Bird
0
0

Why does mapOf("a" to 1, "a" to 2) contain only one entry for key "a"?

hard📝 Conceptual Q10 of 15
Kotlin - Collections Fundamentals
Why does mapOf("a" to 1, "a" to 2) contain only one entry for key "a"?
AmapOf keeps both entries as a list
BmapOf throws an error on duplicate keys
CDuplicate keys cause the map to be empty
DDuplicate keys are overwritten, last value wins
Step-by-Step Solution
Solution:

  1. Step 1: Understand duplicate key handling

    In Kotlin maps, duplicate keys are not allowed; later entries overwrite earlier ones.

  2. Step 2: Confirm behavior of mapOf

    mapOf silently keeps the last value for duplicate keys.

  3. Final Answer:

    Duplicate keys are overwritten, last value wins -> Option D

  4. Quick Check:

    Duplicate keys overwrite previous values = C [OK]
Quick Trick: Last duplicate key value overwrites previous in mapOf [OK]
Common Mistakes:
MISTAKES
  • Expecting error on duplicates
  • Thinking duplicates are stored as lists

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions
More Kotlin Quizzes
Collections Fundamentals - Why immutable collections are default - Quiz 4medium Data Types - Why Kotlin has no primitive types at source level - Quiz 11easy Functions - Named arguments for clarity - Quiz 12easy Functions - Local functions (nested functions) - Quiz 14medium Functions - Vararg parameters - Quiz 6medium Kotlin Basics and JVM Runtime - How Kotlin compiles to JVM bytecode - Quiz 11easy Kotlin Basics and JVM Runtime - Main function as entry point - Quiz 10hard Null Safety - Null safety in collections - Quiz 2easy Operators and Expressions - Range operator (..) and in operator - Quiz 11easy Variables and Type System - String templates and interpolation - Quiz 12easy