Given a nullable list of nullable strings val items: List?, which expression safely gets the length of the first string or returns null if any part is null?

hard📝 Application Q15 of 15

Kotlin - Null Safety

Given a nullable list of nullable strings val items: List?, which expression safely gets the length of the first string or returns null if any part is null?

Aitems?.get(0)?.length

Bitems.get(0).length

Citems!![0]!!.length

Ditems?[0].length

Step-by-Step Solution

Solution:

Step 1: Understand the nullability
items can be null, and its elements can also be null. So both the list and the first element might be null.
Step 2: Use safe calls to avoid errors
To safely get the length of the first string, use items?.get(0)?.length. This returns null if items or the first element is null.
Final Answer:
items?.get(0)?.length -> Option A
Quick Check:
Chain safe calls for nested nullables [OK]

Quick Trick: Chain ?. for each nullable level [OK]

Common Mistakes:

MISTAKES

Using !! which throws exception if null
Missing safe call on list or element
Using invalid syntax like ?[0]

Master "Null Safety" in Kotlin

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions

More Kotlin Quizzes

Given a nullable list of nullable strings val items: List?, which expression safely gets the length of the first string or returns null if any part is null?

Step 1: Understand the nullability

Step 2: Use safe calls to avoid errors

Final Answer:

Quick Check:

Want More Practice?