Working with Arrays and Collections →mediumMultiple ChoiceObjective-mapped

1Z0-829 Working with Arrays and Collections Practice Question

Consider: List<Integer> list = new LinkedList<>(); list.add(10); list.add(20); list.add(0,5); System.out.println(list); What is the output?

⚠ Common exam trap

Watch out — candidates often confuse the `add(index, element)` method with `set(index, element)`, or incorrectly assume that adding at index 0 replaces the first element rather than inserting before it.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

[5,10,20]

The code creates a LinkedList and adds 10, then 20. The third call `list.add(0,5)` inserts 5 at index 0, shifting existing elements to the right. The resulting list is [5,10,20], so option B is correct.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
[10,5,20]
Why it's wrong here
This would occur if add(1,5) were called, not add(0,5).
✓
[5,10,20]
Why this is correct
add(0,5) inserts at the beginning.
✗
[10,20,5]
Why it's wrong here
This would happen if the element were appended, not inserted at index 0.
✗
[5,10,20] but with type warning
Why it's wrong here
No type warning as generics are used correctly.

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1Z0-829 Working with Arrays and Collections Practice Question

Why each option matters

Option-by-option breakdown

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