1Z0-829 Working with Arrays and Collections Practice Question
Which of the following collections maintains elements in the order they were inserted?
⚠ Common exam trap
Many exam-takers confuse 'ordered' (sorted) with 'ordered by insertion' and incorrectly choose TreeSet or PriorityQueue, forgetting that LinkedHashSet is the only standard Set implementation that preserves insertion order without sorting.
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
✓
LinkedHashSet
LinkedHashSet maintains a doubly-linked list running through all of its entries, which defines the iteration ordering as the order in which elements were inserted into the set. This is specified in the Java documentation for LinkedHashSet, making it the only collection among the options that guarantees insertion order.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
LinkedHashSet
Why this is correct
Correct: LinkedHashSet maintains insertion order.
- ✗
None of the above
Why it's wrong here
Incorrect: LinkedHashSet does preserve insertion order.
- ✗
PriorityQueue
Why it's wrong here
Incorrect: PriorityQueue orders by priority, not insertion order.
- ✗
HashSet
Why it's wrong here
Incorrect: HashSet does not guarantee order.
- ✗
TreeSet
Why it's wrong here
Incorrect: TreeSet sorts elements, does not preserve insertion order.
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