[Solved] Given this code, what will be the output?List list = List.of(1, 2, null, 4); int sum = 0; for (Integer n : list) { sum += n; // unboxing happens here } System.out.println(sum); | Java

Java - Wrapper Classes

Given this code, what will be the output?

List list = List.of(1, 2, null, 4);
int sum = 0;
for (Integer n : list) {
    sum += n; // unboxing happens here
}
System.out.println(sum);

ARuntime NullPointerException at unboxing null

BCompilation error due to null in list

CSum ignoring null, prints 7

D10

Step-by-Step Solution

Solution:

Step 1: Understand unboxing in loop with null element
List contains a null Integer; unboxing null causes error.
Step 2: Identify runtime behavior
When loop reaches null, unboxing triggers NullPointerException.
Final Answer:
Runtime NullPointerException at unboxing null -> Option A
Quick Check:
Unboxing null in loop causes runtime exception [OK]

Quick Trick: Unboxing null in collections causes runtime exception [OK]

Common Mistakes:

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