Given two nullable variables a: String? and b: String?, which Kotlin expression safely checks if they have the same content?

hard📝 Application Q9 of 15

Kotlin - Operators and Expressions

Given two nullable variables a: String? and b: String?, which Kotlin expression safely checks if they have the same content?

Aa === b

Ba?.equals(b) ?: false

Ca.equals(b)

Da == b

Step-by-Step Solution

Solution:

Step 1: Understand null-safe equality in Kotlin
The == operator in Kotlin is null-safe and checks structural equality even if one or both are null.
Step 2: Analyze other options
=== checks reference equality, a.equals(b) can throw NullPointerException if a is null, and a?.equals(b) ?: false returns false if a is null, which is not correct if both are null.
Final Answer:
a == b safely checks content equality with nulls -> Option D
Quick Check:
Use == for null-safe content equality [OK]

Quick Trick: == is null-safe and compares content [OK]

Common Mistakes:

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