You have a nullable list of nullable Strings: val items: List?. How do you safely print the length of the first item or print 0 if the list or first item is null?

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Kotlin - Null Safety

You have a nullable list of nullable Strings: val items: List?. How do you safely print the length of the first item or print 0 if the list or first item is null?

Aprintln(items?.get(0)?.length ?: 0)

Bprintln(items[0].length)

Cprintln(items!!.get(0)!!.length)

Dprintln(items?.get(0).length ?: 0)

Step-by-Step Solution

Solution:

Step 1: Analyze nullable types
items can be null, and its elements can be null. So both list and first item need safe calls.
Step 2: Use safe calls and Elvis operator
items?.get(0)?.length ?: 0 safely accesses first item length or returns 0 if null.
Final Answer:
println(items?.get(0)?.length ?: 0) -> Option A
Quick Check:
Safe calls chain + fallback = safe nullable access [OK]

Quick Trick: Chain ?. for each nullable and use ?: for default [OK]

Common Mistakes:

MISTAKES

Using !! which throws exception if null
Missing safe call on first item
Assuming list or item can't be null

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More Kotlin Quizzes

You have a nullable list of nullable Strings: val items: List?. How do you safely print the length of the first item or print 0 if the list or first item is null?

Step 1: Analyze nullable types

Step 2: Use safe calls and Elvis operator

Final Answer:

Quick Check:

Want More Practice?