Which of the following is the correct syntax to use smart casts in a when expression for variable obj?

easy📝 Syntax Q12 of 15

Kotlin - Control Flow as Expressions

Which of the following is the correct syntax to use smart casts in a when expression for variable obj?

Awhen obj { is String -> println(obj.length) else -> println("Not a string") }

Bwhen (obj) { obj is String -> println(obj.length) else -> println("Not a string") }

Cwhen (obj) { String -> println(obj.length) else -> println("Not a string") }

Dwhen (obj) { is String -> println(obj.length) else -> println("Not a string") }

Step-by-Step Solution

Solution:

Step 1: Check correct when syntax
The when expression requires parentheses around the variable: when (obj).
Step 2: Use type check correctly
The correct type check is is String without repeating variable name inside the block.
Final Answer:
when (obj) { is String -> println(obj.length) else -> println("Not a string") } -> Option D
Quick Check:
Correct when syntax uses parentheses and is [OK]

Quick Trick: Use parentheses and 'is' keyword in when [OK]

Common Mistakes:

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