- A
ArrayList: Resizable array
ArrayList internally uses a resizable array to store elements.
- B
LinkedList: Doubly linked list
LinkedList is implemented as a doubly linked list, allowing efficient insertions/deletions.
- C
HashSet: Hash table
HashSet uses a hash table (backed by HashMap) for constant-time operations.
- D
TreeSet: Red-black tree
TreeSet is based on a red-black tree, maintaining sorted order.
- E
HashMap: Red-black tree
Why wrong: Incorrect — HashMap uses a hash table, not a red-black tree. Red-black tree is used by TreeMap.
- F
TreeMap: Resizable array
Why wrong: Incorrect — TreeMap uses a red-black tree, not a resizable array. Resizable array is for ArrayList.
Question 124 of 519
1Z0-829 Working with Arrays and Collections Practice Question
This 1Z0-829 practice question tests your understanding of working with arrays and collections. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Match each Java collection class to its underlying data structure.
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
✓
ArrayList: Resizable array
ArrayList uses a resizable array; LinkedList uses a doubly linked list; HashSet uses a hash table; TreeSet uses a red-black tree. Common confusions involve mixing up TreeMap with ArrayList or HashMap with TreeMap.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ArrayList: Resizable array
Why this is correct
ArrayList internally uses a resizable array to store elements.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
LinkedList: Doubly linked list
Why this is correct
LinkedList is implemented as a doubly linked list, allowing efficient insertions/deletions.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
HashSet: Hash table
Why this is correct
HashSet uses a hash table (backed by HashMap) for constant-time operations.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
TreeSet: Red-black tree
Why this is correct
TreeSet is based on a red-black tree, maintaining sorted order.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
HashMap: Red-black tree
Why it's wrong here
Incorrect — HashMap uses a hash table, not a red-black tree. Red-black tree is used by TreeMap.
- ✗
TreeMap: Resizable array
Why it's wrong here
Incorrect — TreeMap uses a red-black tree, not a resizable array. Resizable array is for ArrayList.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-829 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which 1Z0-829 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Working with Arrays and Collections — study guide chapter
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Working with Arrays and Collections practice questions
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FAQ
Questions learners often ask
What does this 1Z0-829 question test?
Working with Arrays and Collections — This question tests Working with Arrays and Collections — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ArrayList: Resizable array — ArrayList uses a resizable array; LinkedList uses a doubly linked list; HashSet uses a hash table; TreeSet uses a red-black tree. Common confusions involve mixing up TreeMap with ArrayList or HashMap with TreeMap.
What should I do if I get this 1Z0-829 question wrong?
Identify which 1Z0-829 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jun 11, 2026
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