[Solved] What will be the output of this Kotlin code?fun printLength(str: String?) { println(str!!.length) } printLength(null) | Kotlin

Kotlin - Null Safety

What will be the output of this Kotlin code?

fun printLength(str: String?) {
  println(str!!.length)
}
printLength(null)

AThrows NullPointerException

BPrints 0

CPrints null

DPrints length of null string

Step-by-Step Solution

Solution:

Step 1: Understand non-null assertion operator
The !! operator forces the value to be non-null or throws an exception if null.
Step 2: Call function with null argument
Passing null causes str!! to throw a NullPointerException at runtime.
Final Answer:
Throws NullPointerException -> Option A
Quick Check:
Non-null assertion on null = Exception [OK]

Quick Trick: !! throws exception if value is null, use safely [OK]

Common Mistakes:

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