1Z0-829 Working with Arrays and Collections Practice Question
Given: Set<Integer> set = new HashSet<>(List.of(1,2,3)); List<Integer> list = new ArrayList<>(set); Collections.sort(list); System.out.println(list); What is the output?
⚠ Common exam trap
Watch out — candidates often assume HashSet preserves insertion order (like LinkedHashSet) and thus expect unsorted output, forgetting that Collections.sort() explicitly sorts the list into ascending order.
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
✓
[1,2,3]
The code creates a HashSet from a List of 1, 2, 3, then copies it into an ArrayList. HashSet does not guarantee order, but Collections.sort() sorts the list in natural ascending order (1, 2, 3). The output is [1,2,3], making option C 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.
- ✗
[3,2,1]
Why it's wrong here
Incorrect: sorting produces ascending order.
- ✗
Compilation fails
Why it's wrong here
The code compiles successfully.
- ✓
[1,2,3]
Why this is correct
Correct: after sorting, the list is in ascending order.
- ✗
[1,2]
Why it's wrong here
Incorrect: all three elements are present.
- ✗
[1,3,2]
Why it's wrong here
Incorrect: sorted list is [1,2,3].
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